The Kimbell Art Museum is a creation by Louis Kahn, located in Texas. I first encountered it when I analysed the daylight it captures and transforms, as part of a course at University. To give a bit of context, I will quote the words of Wendy Lesser describing both the daylight experienced in Texas as well as its composition within the museum.

“Somehow the harsh Texas sunlight which prevails outdoors has been converted into a cool, silver-tinted beam that bathes the concrete and the paintings and the people who stand in front of them, making everything seem as if it exactly belongs here.” — Wendy Lesser in You Say to Brick: The Life of Louis Kahn

The effect of bringing daylight from the outside and changing the nature of its perception is the power of architecture, perhaps best embodied in the works of Kahn who wrote on the subject:

“The sun never knew how great it was until it hit the side of a building.”

The vault ceilings of the Kimbell Art Museum, often described as “pearly gray”, “moonlit” and, in the words of Kahn himself, “a touch of silver to the room”, are the result of three specific design strategies — the geometry, the material, and the opening through which the light is brought in. But how Kahn prepares the visitors to enter the “silent light” of the museum from the harsh Texas sun outside, by means of a transition, is instrumental to appreciate its effect.

The Transition

Before Kahn designed the Kimbell, the space was an empty site with nothing around, so he had to prepare the visitors to transition from the hot Texas sun to the moonlit interiors where the artworks are displayed. An intentional lighting strategy deployed by Kahn is the transition from the Entrance of the Trees to a deeply shaded portico leading to the museum interiors. Kahn designed the West side of the building as its main entrance, with a grove of ordered trees aligned in parallel creating dotted shades on the lawn. The dappled dynamic shade of the trees slowly merges to the solid static deep shade of the portico.

Our eyes are capable to adapt within a phenomenal range of sensitivity, from 0.2 lux representative of bright moonlight to 100,000 lux of bright sunlight, but they need time for the adaptation. As Stephen Palmer describes in his book Vision Science, “when we enter a dark cinema hall from a bright outside, we cannot see much except the images from the bright screen. After a few minutes, we see people seated near us and after 20 minutes we see the whole theatre surprisingly well”. This so-called dark adaptation is our eyes becoming ten thousand to one million times more sensitive due to chemical changes, than when exposed to full daylight.

The design strategy of transition at the Kimbell does two things to prepare the eyes for dark adaptation: One, it reduces the pace of the visitors by means of the Entrance of Trees which provides partial respite from the unshaded lawn and increases visual interest by creating patterned light. Second, it also reduces the light levels gradually from the brightly lit outside without shade, to partial shade, and finally full shade of the portico into the “silver” light of the inside.

The Geometry

The roof (and ceiling) of the museum is a concrete cycloid vault. A cycloid vault is an extrusion of a cycloid curve, which is a curve traced by a point on the rim of a circular wheel as the wheel rolls along a straight line.

The cycloid vault is not continuous but split into two symmetric halves at its apex with a two and a half foot gap through which the light is brought in. The gap is concealed by a wing-shaped reflector making the vault look mysteriously continuous, the genius of this detail.

Geometrically speaking, the cycloid vault smoothly distributes the light throughout its surface. Irrespective of the time of the day or the position of the sun — high up in the sky or lower down at eye level—the cycloid vault maintains this flat distribution of light.

Take a look at the false colour simulations of the interiors of the museum below. The false colour images indicate the light levels with yellows and reds being a lot of light (>370 cd/m2) and the blues and purples indicating low levels of light (<70 cd/m2). It is not the numbers but the patterns of these false colours that illustrate how the cycloid vault works. Whether it is summer or winter; morning, afternoon or evening, observe how the colours on the vault do not dramatically change from one end to the other end.

If you take the Kimbell Museum away from Texas, which lies 32 degrees North of the equator, and drop it in Singapore, which lies right at the equator (1.4 degrees North), the cycloid vault still works its beauty — it takes the daylight from the outside and distributes it smoothly onto its surface.

The Material

“The pearly gray surface appears to glow from within, especially as it reaches its peak, where the arch disappears under the winglike aluminium brackets…” — Wendy Lesser, You Say to Brick: The Life of Louis Kahn

The material used to build the cycloid vault is grey concrete with a smooth texture. Kahn, with the help of architect Fredrick Langford, would go to great lengths to get the right colour and texture of the concrete envisioned in his mind. While the colour of concrete can range from tints of blues to greens to yellows, Kahn chose a “soft gray with lavender tone” colour for the Kimbell museum vault. To obtain the smooth texture, they conducted numerous tests on the drying time of concrete under the Texas sun.

Now, imagine this colour and texture of concrete as a canvas and light as your paint. With the geometry of the cycloid vault, this light gets brushed down smoothly from its source to the two ends of the vault — and right there you get the “pearly gray” or “moonlit” effect.

The Opening

An opening determines the directionality of the light source within buildings. Thus, irrespective of the sun’s position in the sky, an architect can decide the direction and nature of the source of light brought into the building via modulations of this opening.

At the Kimbell, the opening is a slit, slicing the cycloid vault in two symmetric halves. This central slit is covered by winglike aluminium brackets that diffuse the sunlight and hold the electric lighting. The effect of this opening and the calculated intervention to conceal it are best described by Wendy Lesser when she writes:

“The sunlight coming through the central slit […] turns into a silvery glow on the uppermost reaches of the finely textured concrete. The effect is glorious, but it is definitely an effect, a calculated invention to make you feel that light is being shed from an unseen source.”

The central slit, aluminium brackets and the electric lights combine to form a complete light source for the artworks displayed in the Kimbell. With such minimal but precise devices for combining daylight and electrical light, experts say, the resulting colour temperature (3500K to 3800K) at Kimbell is the “sweet spot” for viewing colour. And once again from Wendy Lesser who describes the colours of the artworks displayed at the museum:

“Here, landscapes have the feel of being actually outdoors. Interiors and portraits glow. Pastel colors gain an added strength, and white highlights leap forward.”

The light of the Kimbell is a synthesis of synergic textures and simple techniques with calculated detailing and a thoughtful design process, mindful of how people move and experience space.

My analysis of light at the Kimbell is informed by simulations, testimonies of visitors who observed the light in the museum, my engagement in the growing discussions of qualities of light and my years of working towards a PhD in daylighting. But it is remarkable that Kahn, without any simulation tools to quantify or visualise light, and working against the styles of his period, brings these profound and timeless qualities of light and space in his works. Kahn’s experienced intuition to design, remarkable observations of historical buildings and a team of experts who believed in his vision made it possible to create a building like the Kimbell Art Museum.

It became my signature walking tour for all my visitors in London. I would start at the North-South axis and go along Peter’s Hill all the way until the end of the Millennium Bridge. At several fixed spots, I would tell them to turn back and look at the changing perspective of the St Paul’s. The final turning point — the wow point — was at the end of the Millennium Bridge, where all lines of the bridge’s vanishing point in perspective lead your eyes to the towering and majestic dome of the St Paul’s. The view is prismatic in multiple dimensions.

It is only recently that I discovered the St Paul’s views were not a coincidence. It is in fact the result of a much articulated piece of policy by the City of London Corporation called the St Paul’s Heights (a part of the Protected Views Policy), operated since 1937. The policy lays down height and setback restrictions for buildings in the surrounding region to maintain eight axes viewpoints towards the St Paul’s dome. In addition, one viewpoint is 19 km away from the St Paul’s at the King Henry mound in Richmond’s Park.

Each time I took my friends/visitors along for the walk, they would have a revelation. Not only because the views were amazing but because it would have never occurred to them to appreciate a building or a cityscape in this manner. While I realize that for us architects, appreciation of a city view, building or a space comes instinctively, note that most of my visitors were not trained as architects. But anytime you see someone with a camera craning their neck sideways, twisting their bodies or positioning themselves front and back like a zoom lens in front of building, you can guess they are either professional architectural photographers or disciples of architecture.

Which brings me back to the original intent of this post — spaces for perspectives. This is a call out to policy makers, urban planners, architects and aspiring urban explorers alike. Cities are captivating when people can appreciate them from different perspectives. These perspectives come from an amalgamation of three things: designing buildings with multiple vanishing points; providing diverse spaces to appreciate the city from; and taking advantage of natural contours or planning level differences from the ground up.

Buildings with multiple vanishing points

A historic city that has had a chance to age well — with layers of additions, winding streets, non-grid plans, adept policies and keen city dwellers wanting to unlock every aspect of the city — naturally offers many spaces to view and appreciate the city from. And what makes a historic city give this multitude of views is essentially described in The Urban Sketching Handbook by Stephanie Bower:

When buildings are rotated or skewed in plan, as they often are in older cities that were not built on a grid, you will likely find multiple vanishing points along your eye-level line.

Anyone who has attempted to draw a perspective of any three-dimensional object or space should be familiar with the term of vanishing point. It is an essential concept to depict the direction of a view, its depth and scale in a perspective drawing. A picture is worth a thousand words, so take a look at the image above — a comparison of vanishing points on a street in Singapore versus a street in Edinburgh.

In a street perspective, where all the lines are parallel — roads, pavement, building block, overhangs, extensions — you get one vanishing point. Your eyes are led to this one point in infinity, where there is nothing to expect. Nothing in the perspective of the street arouses your curiosity to find out what could be at the end, though it is perfect for a commercial street like Orchard Road in Singapore. The one vanishing point and its parallel lines keep a pedestrian’s eyes on the storefronts and their contents, away from the visual excitement that a street can bring.

Add more vanishing points and your eyes are led instead to multiple attractive foci. The street speaks directly to you, corners telling you “Turn around me!”, each building peeking out from its grid asking “Hey, how do I look from this side?”, this curve on the road prods you “Where do I lead?” With multiple vanishing points the street itself becomes the exciting shopfront with never-ending opportunities to be discovered anew. The street is brought to life.

Take it from Flâneuse by Lauren Elkin, describing the desires when walking a street in a city:

Give me drama. Give me unexpected curvilinear corners. Give me unsettling churches and beautiful store fronts and parks I can lie down in.

Contours in a city

A city that takes advantage of its contours has layers of opportunities to be explored. By contours I mean the outlines of level differences of a land mass.

Take Edinburgh in Scotland, a city built in keeping with its natural contours. Walking down its streets, you will notice roads peeling away rather unexpectedly downwards or upwards, revealing its layers. There are steps from the side of the streets that take you to divergent pathways and nooks going up or down. You never expect it nor see it coming because it is never at your eye level and when it suddenly appears, it urges you to follow its slope to see what unfolds.

The playfulness of the city does not stop there. It is a historical city with winding lanes that narrow down and open up, offering multiple vanishing points and moments of surprises. Let me not even begin to describe its landscape. Edinburgh is tucked by hills on one side and by sea on the other. Crossing a junction sometimes brings a confused attraction to both the rolling hills and the sky-kissed horizon over the sea.

Edinburgh is a historical city without the dredge of having to maintain a high density population. Its horizontal sprawl, helped by its contours, adds to a shifting perspective between a bird’s eye view and a worm’s eye view of its buildings and landscapes. But what about the contours of a high-density city? Well let me take you to the cityscapes of Hong Kong!

Hong Kong is one of the most densely populated cities in the world. Below is a photograph of the road leading from the airport to the city. Those tall towering buildings are not only impressively tall, they also lace on to natural contours. Walking into the heart of the city, it is difficult to even catch a glimpse of sky at your eye level.

Naturally occurring steep contours provoke shifting eye levels, but it is the man-made level differences that really stand out in this densely packed and notoriously tall cityscape.

“Footbridge networks throughout the city that grew piecemeal, built by different parties at different times to serve different immediate needs, eventually formed an extensive network and became a prevailing development model for the city’s large-scale urban projects.” — Cities Without Ground: A Hong Kong Guidebook.

These stretches of pedestrian bridges — or footbridge networks — crisscrossing at several heights, through multiple buildings (both private, commercial and administrative), spanning large varied parts of the city (ports, bays, parks, squares, markets, transit stations, shopping malls, streets, just about everywhere) create an intrinsic network of never ending spaces to appreciate the city from.

Spaces to appreciate the city from

In Hong Kong, it is the man-made level differences — the network of pedestrain bridges — that doubles up as the very spaces from which the city can be taken with all its dynamism. These spaces are not just the static levels that split the city but also the transient means to get there. The linear stairs, spiral stairs, escalators, moving walkways, bobbing elevators are all spaces where one can catch several glimpses of hidden details that the city offers.

Looking up a building from the ground is not the same as meeting it at eye level, nor is it the same as looking down at it. You would be surprised at the various levels of details revealed from each angle you view a building or a composition of buildings.

Take the Concourse building in Singapore (pictured above). It is a hexagonal building with beveled windows looking downwards. Looking up at it from the ground level amplifies the proportion of the bevels. Observe it from the overhead pedestrain bridge six meters above ground and you will see the undulating waves of its hexagonal extensions, flushed with the tropical green canopy and its background context. Now walk away from the Concourse for about a kilometer and turn back to see the beveled windows disappearing to become alternating stripes. This is what excites me about changing perspectives — a new outlook, a new layer of detail, a new level of information, a new composition with a building that never changed. Imagine the possibilities of this exploration.

So be it an old building like St Paul’s in a historic non-grid city like London or be it a modern building like the Concourse in a newly developed city like Singapore, or be it a building yet to be be designed in a perfect grid layout, there are always opportunities to create attractive cityscapes. Add some vanishing points, create contours/levels or design more spaces to view buildings with their changing angles and context. And never forget to look up, look down or turn back one last time before exiting a street for the surprise view it holds!

Then I happened to pay a visit to one of the many sprouting shopping malls. Given my love for the outdoors, I am not a great fan of the mall — it is a visual and sensory maze designed to make sure you remain inside, indoors for extended hours. If it was up to me, I would tear apart the mall and iron out all its content onto street fronts, adding to an even greater and richer sensory experience. But the urge to do so gave in, here in this small town. In the mall I felt a sense of secure independence from the immediate outside: there were more women here, walking a slower pace, sitting down at the mall food courts and having a chat, admiring aisle after aisle of organized commodities in the supermarket. Everyone, women and men, had a different behavior in the mall.

To understand this difference in behavior, allow me to paint a picture of the streets of this town. Most of these bustling town centers are packed with lines of one or two storey shops. There are no well-defined sidewalks. People and cars walk hand in hand with each other. The streets throb with the cacophony of horns mixed with call-outs of vendors and shopkeepers, predominately men, who in Jane Jacobs’s terminology would be the “eyes of the street”. Let me add to that — eyes, voice and ears of the streets as well. With this and the position that men enjoy in such social systems, the streets become a platform for them to be the way they want to be. They wait, sit, squat, observe, group up or ogle at passersby and if the passerby in question is a woman, especially a younger woman by herself, then some may resort to showcasing their talents of whistling, singing, or flirting. But all this changes within a shopping mall and I attribute it to two reasons — the light and the structure of the space.

Let me elaborate. Lights in a mall are chosen and placed to make the products and the mall itself appealing. A dark and shady mall becomes an enclosed and rather suspicious place to be in. Thus the lights are intentionally picked to be blazingly white and uniformly light the mall up. This makes everyone conscious, like one was in a spotlight. Second, the shops are stacked vertically around a central atrium, making sure the sight lines can intersect among all floors and all angles. This is also a marketing strategy: the more visible you can make shops at different floors, the more you force the flow of customers to all the shops in the mall. In short, a shopping mall is a design concept intended to make you walk longer, so that you can see more, stay more and spend more. But it is these very strategies that also induce a more formal etiquette in the mall, here and wherever one is found. There is an urge to dress better and behave better because of this sense of being watched.

The change is simple: men unfamiliar with this feeling outdoors suddenly tame down their “street instincts”. And women, ever so used to being watched, feel at ease for once: to gather, to talk, to stroll and just be. After a taste of this freedom, it is only a matter of time until women make the streets their own.

The rise of the department store, in the 1850s and 60s, did much to normalise the appearance of women in public; by the 1870s, some guidebooks to London were already beginning to feature ‘places in London where ladies can conveniently lunch when in town for a day’s shopping and unattended by a gentleman’ — Lauren Elkin, Flâneuse