This remarkable proposal suggests a framework to accommodate present as well as yet-unplanned programs rather than a fixed-use, single-purpose structure.

This proposal for a pedestrian bridge in Amsterdam doubles as a public park with wildlife, recreation, a cafe and even a sloped roof for sledding in winter.

A tiny traditional Korean house is wedged between two more conventional buildings in Liverpool, England, in artist Do Ho Suh's installation 'Bridging Home.'

Turn the pages of this sweet little pop-up book one by one and you'll see a busy city sprouting and growing before your eyes.

An artificial pavilion gives the Dutch city of Almere an extra 111 acres to host a horticultural festival and expand for new homes, offices and a university.

This 'rest station' for a busy Paris street offers chairs with desks and electrical outlets, a touch-screen information center, free wi-fi and a green roof.

Dutch designers create miniature 'trash villages' in urban locations by transforming dumpsters into bars and restaurants using discarded building materials.

Far from prohibiting skaters, these 13 temptingly skateable structures - from house interiors to museum rooftops - were designed with skateboarding in mind.

An organization called '3Space' in the United Kingdom matches landlords of vacant properties with groups who need to use them, free of charge.

Even for difficult-to-surprise native New Yorkers, the hidden NYC that Alex MacLean captured in his new book might be something completely new.