How Did They Build That?

An unstable high rise, an otherworldly museum, and a towering cliffside elevator.

A Manhattan high-rise; an Athens cultural center; a Singapore university.

A London railway station; giant Singapore biodomes; eye-catching hospital in Las Vegas.

A towering bridge in France; upside-down hotel in China; Italy's forest into the sky.

Alien port authority in Belgium; ultrathin skyscraper in Manhattan; hanging museum in Scotland.

The inside stories behind a new, horseshoe-shaped complex in Rotterdam, a rock-shaped opera house in China and a makeover of the British Museum.

The engineering secrets behind a massive sky garden in Singapore, the world's most slender tower in Brighton, and a railway station in the shadow of Vesuvius.

The engineering secrets behind a mobile research station in Antarctica, a gravity-defying concert hall on the Canary Islands, and a rotating boat lift in Scotland.