On a small Puerto Rican island, banks of secret naval bunkers lie abandoned and filled with piles of office equipment.

The "Seinfeld" diner.

A hands-on traveling collection of the innovative devices of yesteryear.

Elevated freight railway turned wildly successful urban park.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

A terrific purveyor of natural history objects and curios.

A flooded Mexican cave that hides a river beneath the water.

Week-long block party becomes a competition for the best decorated street.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.