Romans built the world's tallest artificial waterfall in 271 BC.

Old Danish castle immortalized in Shakespeare's Hamlet.

This sublime architectural marvel is a rare example of an expressionist church.

Copenhagen's celebrated theme park and gardens.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

An underground city of salt.

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

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

A centuries-old forgotten underworld lies beneath Malta.

This Stone Age solar temple aligns with the sun on each equinox and solstice.

Overshadowed by other, more famous Maltese catacombs, this ancient burial chamber has one of the best examples of a ritual agape table.

Abandoned Roman Catholic chapel abused by Satanists before being restored.

The remains of a 1st-century aristocratic Roman town house featuring beautiful well-preserved mosaics.

This unique building in the main square stands out among the city's typically Baroque architecture.

These lesser-known Maltese catacombs date back over 1,700 years.

The ruins of a megalithic monument sit right in the garden of a luxurious Maltese resort.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

A circle stone within a stone circle.

An octagonal folly tower overlooking the sea.

A fantastic castle rumored to be the birthplace of King Arthur.

One English town's celebratory landmark spurred more trouble than anticipated.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

A fascinating insight into daily life in the Eastern Bloc.