

Visiting Australia's One Central Park, the Oslo Opera House and the California Academy of Sciences in San Francisco to reveal their architectural secrets.

Engineers grapple with an apartment building, ripped apart by a man-made canyon; the Gateway Arch takes shape in St. Louis; an unpromising plot in Copenhagen, Denmark, is transformed by a gleaming new triangular office.

A museum building bends 1,100-glass tubes to form a facade and tunnels below the water table; a vast 11-storey glass atrium HQ is built on the former Berlin Wall site to represent unity.

Lord Foster's five-winged steel towers cool Abu Dhabi's national museum naturally. Robots 3D-print a steel bridge in Amsterdam & a concrete tower in Switzerland. And in Sydney, engineers pump out the harbour to build a fish market.

NASA's 3D-printed Mars habitat rehearses human life on the red planet. Seoul's historic city hall gains a 13-story glass wave. And in Dallas, 68,000 square feet of concrete galleries balance on legs that want to splay open under.

Building an eco-friendly visitor center in the permafrost on Colorado's Pikes Peak tests the team. A museum is constructed in a disused dry dock that's in danger of collapse.

A new performance center with a tent-like glass-and-steel lobby tests engineers in Kansas City; two twisting apartment towers make heads spin in Ontario.

Investigating the 2009 crash of Colgan Air Flight 3407; the plane stalls at low altitude and dives into a residential area near Buffalo, N.Y.