The world's biggest pet store.

An industrial relic is now one of Europe's most staggering art spaces.

This massive steel pyramid can be entered by a set of jagged steps that let visitors stand in its heart.

No need to strap in for a "ride" on this walkable roller coaster.

This former steel and coal plant is now a neon-lit industrial fantasia.

This colorful but controversial ceiling has been likened to a 21st-century Sistine Chapel.

These enduring murals depicting a distinctly Marxist tribute to capitalism could not even be defeated by McCarthyism.

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

A unique Shinto shrine filled with bunnies and wordplay.

Home to the world's oldest wooden building.

Over 2,000 ancient temples dot the Myanmar landscape at the site of this famed archaeological site.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

A relic of Victorian grandeur hides beneath a busy South London road.

Moscow's imposing monument to the Space Age.

Stalinist skyscraper built with help of cryotechnology.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

A former squatter's paradise outside Prague.

A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

Abandoned 18th century weapons factory in the Aezkoa Valley.

Abandoned Nazi train station turned underground astroparticle laboratory.

32,000 tiny soldiers are posed in 23 historical settings.

This religious complex carved into a cliff is steeped in legends of miraculous stags and the Holy Grail.

A Franco-era dam flooded (almost) everyone out of this centuries-old Aragonese town.

Nancy Thompson's Home from "A Nightmare on Elm Street."