A secret climbing tree hides along the side of a Costa Rican road.

During the Soviet era, the spire of this longstanding church was used as a radio transmission tower.

Walk along the medieval fortifications that have been protecting Tallinn since the 14th century.

One of the two original gateways into the Kasbah, this gateway is a nesting site for storks.

Traditional 11th-century outdoor tannery.

A fortified city, home to a remaining population of five families

Mosaics, storks, and brothels—this ancient city has it all.

Fortune tellers, snake charmers, poets, and storytellers all gather on this historic square in Morocco.

One of the most spectacular canyons in the world.

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

A lush indoor jungle fills this bustling Madrid transportation hub.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

Dynastic Home of the De Piro Family.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

Stone Age solar temple is aligned with the sun on each equinox and solstice.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

France's most famous cemetery, with some of its most curious tombs.

This Hungarian stilt village is built in a lake that never freezes over due to the power plant that that uses it as a cooling pond.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

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

Macabre astrological automaton clock dating to the late 1400s.

This centuries-old wooden wonder was built in less than a year and is one of Europe's largest timber-framed churches.

The reason for the strange contortions in the trunks of these "drunken" pine trees in Russia is still a mystery.