Seattle Skyline

It is an observation tower, built for the 1962 World's Fair, and the whole thing went up in under a year to make the opening. The foundation is the part worth knowing: a hole 30 feet deep and 120 feet across, filled with 5,850 tons of concrete, so that the structure's centre of gravity sits only about five feet above ground level. It is engineered to stay put in high wind and seismic movement by being anchored like a weight rather than braced like a frame.

At 605 feet it is no longer close to the tallest thing in Seattle, and it is still the first shape anyone looks for. A model that gets the saucer's proportion or the leg taper slightly wrong stops reading as Seattle immediately.

Seattle sits near the Cascadia subduction zone, and its towers are designed for earthquakes in a way that visibly shapes them. The Columbia Center's dark, curved, stepped mass is a seismic response as much as an aesthetic one, and Smith Tower — 1914, and the tallest building west of the Mississippi for nearly half a century — survives from an era with entirely different assumptions, its white terracotta and pyramid cap looking like it belongs to another city.

Between the two sits most of Seattle's recent construction, driven by a tech boom that has reshaped the downtown skyline faster than anywhere else on the west coast.

The Columbia Center is the tallest at 933 feet, three curved black segments stepping back from each other. Rainier Tower sits beside it on its famously tapered pedestal base, a building that looks balanced on a point.

The Space Needle stands well apart from the downtown cluster, at Seattle Center rather than among the towers, which is a spacing most models get wrong by pulling it in. Smith Tower closes the southern end — white terracotta, a pyramid cap, and from 1914 to 1962 the tallest building west of the Mississippi. The Olympic range sits behind everything on a clear day, which is roughly a third of the year.