Petrified footprints of one of the very first vertebrates to walk on land.

This single room has survived the centuries with almost no deterioration.

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

This museum in the famously blue neighborhood of Sidi Bou Saïd showcases a traditional Tunisian lifestyle.

An ancient Phoenician citadel once stood at the site where Queen Dido first landed, according to legend.

An ancient burial ground believed to have been used for ritual sacrifice.

The ancient heart of Tunis is an enormous maze of narrow streets and alleyways.

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

In the sleepy town of Gozo exists a reproduction of the entire town of Bethlehem.

At more than 5,000 years old, these structures are among the oldest free-standing stone buildings in the world.

These temples are among the oldest free-standing stone buildings in the world.

This 50-foot-deep sinkhole created in the 14th century is home to rare plants and fungi.

This almost-forgotten underground dungeon housed several convicts over the years, including Caravaggio.

The fishing boats that moor in this small lagoon enter and leave through a tunnel to the sea.

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

The Jesus tree of Malta bears a striking resemblance to Christ on the cross.

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

A centuries-old forgotten underworld lies beneath Malta.

This subterranean necropolis holds three floors of antler-dug grave caves.

A hidden tunnel of bones in one of Malta's oldest churches.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

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

The vertical-axis windmills of ancient Persia have been grinding flour for 1,000 years and counting.

Thousands of well-dressed mummies below a monastery.