2300-year-old Roman road connecting the empire.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

See replicas of Europe's most famous cave paintings and even some of the animals that feature in the art.

A spectacular walk on the flank of a gorge.

An abandoned Indian-inspired mansion.

A historic Christian shrine nestled within a spectacular natural cave.

A site where “the ravages of the war are more striking…than any other place in contemporary Spain.”

The world's largest sundial can cast a shadow more than 1,600 feet long.

The facade of this 16th-century building is decorated with carvings of 300 seashells.

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

Walls of stone rise up from sinkholes caused by underwater erosion.

Two large eyes painted anonymously on a mountain overlooking the city pay homage to an old legend.

Geological storytelling.

Cliffside houses provide a spectacular view from their perch above the valley.

For more than half a millennia, this automaton has rung an hourly bell.

The most elaborate of 12 medieval arched doorways to the old city of Burgos.

This remarkable museum sprung from one of the most important prehistoric archaeological sites in the world.

The gaunt visage of this angular Christ giant is enough to put the fear of God into all who see it.

A pair of gigantic baby heads greet passengers at Atocha Station.

A neighborhood represented by an apparent geocentric and flat-earth model of the Solar System is hidden in the subway of Madrid.

This grand gate once marked the entrance to a military barracks.