Rare karst landscape eroded from a flat seabed.

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

A New York–based physician returned home to Spain to build his own elaborate monument to Christopher Columbus.

Haunted tuberculosis hospital built by the patients.

No shoes allowed on this trail, which is designed to be experienced barefoot.

This 47-story "M" needed 20 years to be completed

Legends surround this natural rock formation that looks like a Moorish king wearing a crown.

A monument at Alicante Marina honors a little-known hero of the Spanish Civil War.

This enormous sardine in the Segura River pays tribute to an annual post-Lent tradition.

Abandoned Nazi train station turned underground astroparticle laboratory.

The two massive guns that defended Cartagena Bay.

The 20th-century church looks like a rustic version of the Sagrada Familia.

Originally planted by the ancient Carthaginians, this sprawling palm grove is one of the largest in the world.

Down this yellow brick road, visitors are treated to toadstool houses and massive mushroom sculptures.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

An encyclopedic collection of mammal penises.

Ship-sized kinetic sculptural fantasy.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

South Carolina's last remaining slavery auction house is now a museum devoted to its own tragic history.

One of the oldest living oak trees in the Southeast.

Despite being burnt down multiple times, the ruins of this South Carolina church are still standing.

A much more welcome kind of snowbird vacationer, manatees camp out in these springs every winter.

Off of the Crawfordville Highway in Florida, nature is taking back this decrepit row of Ford trucks.

This phone booth-sized municipal building has been a piece of police property for more than half a century.