The largest coin pyramid in the world is a carefully balanced stack of over 1,000,000 pieces.

This former KGB building is now a museum memorializing the people who suffered during the Soviet regime.

Over time, this castle grew to encompass the entire island.

An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

The nearly 200-year-old folly has a secret spiral staircase hidden in one of its pillars.

This medieval manor house was hastily fortified when it found itself in the middle of the Scottish fight for independence.

This sandstone tree trunk is a relic from a long-past era when England had a more tropical climate.

Though this bridge was originally built in the 12th century, only one of its 10 arches dates back that far.

The former "holiday home" for monks at the Durham Cathedral.

A monument with a strange legend involving a horse's tongue.

Huge winged monument in the United Kingdom.

Journey through this open museum where even employees remain true to period.

The world’s oldest surviving single-arch railway bridge.

These giant sculptures are supported by a bizarre menagerie of feet.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.