Commemorating the spot where the famous scientist fed his pigeons.

NYC's legendary underground network for bovine transportation.

One of the last Jazz Age "Wonder Theaters" in New York City.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

Morocco's Argania trees are infested with nut-hungry goats.

World's largest film studio, where visitors tour the decaying sets that litter the harsh desert environment.

This wildly-tiled artist's palace is a living and growing account of the creator's life, loves, and labors.

A kaleidoscopic warehouse-maze of handmade neon signs.

A corkscrew-shaped barn in Ireland.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.

The first skyscraper to include a Ferris wheel built into the facade.

A small museum in this border city displays the contraband art that has been stolen back from smugglers.

Boats must transform into railroad cars to navigate this Polish canal.

A program of Communist glamour in post-Stalin Poland is preserved in this colorful museum.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

A 20th-century picture show in 3-D.

The largest manmade caves in Europe now function as a motorbike club's headquarters.

This unusually shaped mountaintop tower looks like a UFO floating over the city.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

A church of bones, decorated with 40,000 human skeletons.

This outsider art house has gone from clinical creation to astounding artwork.

On a winding Vienna side street, one museum has turned their windows into a monument to history’s peace-minded heroes.