Longest canal tunnel in the world, abandoned in the 1960s.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

World's largest working waterwheel has been around for over 150 years.

A prison tower–like edifice honoring a beloved local benefactor.

A 150-year-old steam locomotive crosses the southern half of the island daily.

This hidden bridge is where local children leave gifts and messages for the island's fay folk.

A guitar mounted on a wall in Temple Bar honors the Irish musician.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

A tall karst islet popularized by 007.

Modern design and unusual architecture make this mountaintop temple no ordinary Buddhist retreat.

Where an entire elephant skeleton, a snakeskin table runner, and thousands of animal remains become art.

A small museum in the Golden Triangle tells the story of the opium drug trade that gripped Northern Thailand.

India's first open-air public art district sits in the heart of the country's capital.

The mysterious empty cupola behind the monumental arch points to an ancient prophecy of Delhi.

A blooming house of worship for the masses.

Many Hindus make the long pilgrimage to this holy city to have their remains burned on the banks of the Ganges River.

A white Buddhist temple with a golden restroom.

Riding on a pair of architectural dragons, this Thailand temple holds murals full of lurid imagery.

An amalgam of precariously balanced boulders, ancient petroglyphs, and Buddhist shrines.

Hoax, mistake, or evidence of dinosaurs in human times?

A battle between nature and architecture in the Cambodian jungle.

American bombs, morbid memorabilia, and graphic photographs tell the story of the CIA-led “Secret War” from the Pathet Lao perspective.