A mysterious Castle is now home to a rare breed of goat.

The ruins of a stone tower with alleged (but unlikely) Roman origins.

Visit the ruins of a magnificent mansion confiscated by Fidel Castro.

This formerly-prosperous Silesian mining town was completely demolished in the late 1960s and early 1970s as an attempt to cover up a secret Soviet uranium mine.

The world's longest known cave system.

Prehistoric animals decorate this popular outdoor park.

A former 19th-century tavern, famous for its peach brandy and honey concoction.

Amazing taxidermy dioramas from the 1960s in a cement building meant to look like an ice cave.

This cave overlooking the Indian Ocean has been turned into a shelter and makeshift museum.

This ancient cave is home to a museum, bar, and is filled with fluorescent minerals.

This ancient burial site was once thought to be the home of a race distinctive to Ainu folklore.

The last occupied troglodyte dwellings in England weren't abandoned until the 1960s.

A museum to a cave explorer whose tragic death was a media sensation, and whose corpse became a tourist attraction.

The last of Amsterdam's original sea level markers remaining in place.

This structure, built more than 60 years ago to manage devastating seasonal floods, is known to attract a rare species of freshwater dolphin.

This large copper bolt represents the benchmark for measuring sea levels in most of Europe.

A huge museum of much more than just agriculture displayed in a princess's palace.

A preserved oasis with traditional Andalusian-style architecture and beautiful views of the Nile.

Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

Hundreds of thousands of ancient documents offer a unique glimpse into Jewish life in Cairo.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

The curios of pharmacist and collector Henry Wellcome.