The world's tallest timber residential tower, 10 stories, in currently in Melbourne, Australia, though a 14-story Norwegian project may top it in 2015. Courtesy of Lend Lease hide caption

itoggle caption Courtesy of Lend Lease

This concept image shows an aerial view of the proposed Zootopia in Denmark. The designer says the idea is to let the animals roam free, separated from visitors by hidden barriers. Bjarke Ingels Group hide caption

itoggle caption Bjarke Ingels Group

Interns who host tours on Capitol Hill, stopping at sites like the small Senate rotunda, don't always have their facts straight. The Architect of the Capitol hide caption

itoggle caption The Architect of the Capitol

The Shard, the tallest building in Western Europe at 1,016 feet, was inaugurated in London in 2012. It got its formal name when the builders adopted the term used by critics, who called it a "shard of glass" in the city's skyline. Ben Fitzpatrick/AP hide caption

itoggle caption Ben Fitzpatrick/AP

Architect's rendering of Apple's new facility Courtesy of City of Cupertino hide caption

itoggle caption Courtesy of City of Cupertino

Sky City, a replica of Paris, is a 40-minute drive from Hangzhou in East China's Zhejiang province. The rich people that developers hoped would move here never materialized. Frank Langfitt/NPR hide caption

itoggle caption Frank Langfitt/NPR