This faux-seedy Japanese arcade is made up to look like a maze of alleys straight out of a cyberpunk dystopia.

An abandoned railroad tunnel is now filled with bioluminescent bugs.

Building owners can take out tiles for free at this repository for historic building materials.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

One of Antoni Gaudí's least-visited works, an homage to Catalan patrimony that mixes neo-Gothic with Modernista forms.

One of Europe's largest supercomputers is housed inside of a disused chapel.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

A small peaceful park and waterfall tucked amid the urban grind of Midtown Manhattan.

This futuristic airport terminal was abandoned for decades before reopening as a hotel—with a vintage plane of its own parked out back.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

This hilltop park offers magnificent views and a Frank Lloyd Wright masterpiece.

Charles Babbage's proto-computer, painstakingly brought to life.

The lab where the scientist made his groundbreaking discoveries is preserved on the basement floor of the Faraday Museum.

The remains of Crystal Palace Great Exhibition of 1851.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

This stockpile of junked electronic and mechanical gadgets is a favorite among Hollywood prop masters.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

This forgotten Frank Lloyd Wright house is an architectural marvel at the end of a sleepy residential street.

Most famous work of one of Frank Lloyd Wright's sons.

This weird abode has inspired everything from the "House On Haunted Hil" to a robot hunter's pad.

The legendary building that needed ghostly approval before being built.