Canton Tower

Stand at the base and tilt your head back. The tower does not rise straight. It twists. Thin white steel tubes spiral upward in two directions, crossing each other again and again, and the whole form narrows near the middle before it widens again higher up. On a humid Guangzhou afternoon the air feels thick and warm, and the river breeze carries the smell of water and traffic. Somewhere above you, small capsules are moving slowly along the rim of the tower.

This is Canton Tower, on the south bank of the Pearl River. It opened in 2010, the year Guangzhou hosted the Asian Games. The city wanted a new symbol for that moment. It wanted something that people would recognise from the river, from the airport road, and from photographs. The result is about six hundred metres tall to the tip of its antenna. For a short time it was the tallest television tower in the world, before Tokyo Skytree passed it.

Locals have a nickname for it. They call it Xiaomanyao, which means something like slim waist. You can see why. The structure is wide at the ground, pinched in the middle, and wider again near the top. Many people compare it to a dancer turning, or to a person twisting at the hips. The nickname is affectionate, and you will hear it in taxis, in markets, and on local television.

The design came from a competition. The winning team was a small Dutch practice called Information Based Architecture, led by Mark Hemel and Barbara Kuit. The engineering firm Arup worked on the structure. Their idea was simple to describe and very hard to build. Start with two ellipses, one at the ground and one at the top. Rotate the top ellipse against the bottom one. Then connect them with straight lines. The twist creates the curve.

Here is the first surprise. Every main column you see is straight. None of them actually bends. The curving shape comes only from the way straight tubes lean and cross at different angles. Mathematicians call this kind of form a hyperboloid. You may know it from power station cooling towers. Here, the same principle carries a tower of steel. Inside the outer lattice there is a concrete core that holds lifts, stairs, and services.

That open lattice also does practical work. Wind can pass through it instead of pushing against a solid wall. Guangzhou sits in a region that sees typhoons, so this matters. The gaps between the tubes also let daylight fall on the inner core, and they let visitors look out through the steel at many levels. From the outside, the tower looks light. From the inside, you feel the frame wrapped around you.

Now think about the city around it. Guangzhou is one of the oldest trading ports in China. For centuries, merchants from many countries came up the Pearl River to trade tea, silk, and porcelain. In English the city was long known as Canton, which gives the tower its name. Today the river is still the city's backbone. Ferries, cruise boats, and barges move along it day and night, and the tower stands at a bend where many of them pass.

Look across the water to the north. That cluster of glass towers is Zhujiang New Town, the modern business district. Between those towers runs a long open plaza, Huacheng Square, which lines up with Canton Tower across the river. Planners designed this axis on purpose. The old city, the new business district, the river, and the tower all sit along one line. If you walk that plaza later, you will see the tower framed at its far end.

Now the second surprise, and it is at the very top. Most observation towers put their Ferris wheel on the ground. Here, it runs around the edge of the roof, high above the city. It is called the Bright Spark wheel. Its glass capsules travel slowly along a sloping track at the rim, so riders circle the summit while they look down on the river. It is a strange and gentle ride, and it moves slowly enough that most nervous visitors still enjoy it.

For people who want something faster, there is the Sky Drop. Riders sit on a ring of seats near the top of the mast. Then the seats fall down the antenna in a short free-fall, before brakes slow them. You may hear the screams from the deck below. Between these two extremes there are indoor and outdoor viewing levels, places to eat, and a restaurant where the city turns slowly past the windows.

Most visitors come back after dark, and for good reason. When the sun goes down, thousands of lights along the steel tubes switch on. The tower changes colour, sometimes slowly and sometimes in fast patterns. Rainbow bands move up the lattice. On holidays the light shows can carry special colours and messages. On the river, the cruise boats slow down so their passengers can photograph it. The reflection in the water can be as striking as the tower itself.

Sit for a moment and listen. Down here you hear the road, the metro, the murmur of families and school groups, and vendors selling cold drinks. Up there, the sound is very different. The higher you go, the quieter the city becomes. The traffic turns into a soft hum. On a clear day you can see the river curving away toward the delta. On a hazy day, the towers across the water fade into grey layers.

It is worth remembering what this tower does beyond tourism. It was built as a broadcasting tower, and its antenna serves television and radio. So every day, as people ride the wheel and take photographs, signals pass through the mast above them. It is both a working structure and a public landmark. Many towers around the world share this double life, but few twist like this one.

Before you leave, look up once more from where you are standing. Follow one white tube with your eyes, from the ground to where it disappears among the others. Notice that it never curves. Then step back and see the whole shape bend anyway. As you walk toward the river, turn around after a few minutes. From a distance, the slim waist is easy to see. And if the lights are on, watch the colours climb the steel as the city carries on around you.