Rebuilt remains of a temple to Roman god Mithras.

An alchemist's "magic door" stands in the middle of a Roman park.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

The atmospheric road was never meant to be so creepy.

A 30-acre garden inspired by the principles of modern physics.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

The palace of the King of Kings, burned by Alexander the Great.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

The ruins of an ancient Zoroastrian Tower of Silence believed to be the earliest example of the traditional funerary practice.

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

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

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

The ruins of a medieval village that was abandoned after a 19th-century inferno.