An icy lake tucked among jaw-dropping alpine panoramas.

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

This ancient Spanish castle sits high upon a hilltop.

Mine shafts and hard pastries await visitors at this massive mountain of salt.

Stunning Roman aqueduct used for 1900 years and still standing.

Archaeological site of Iberian people ruins.

This medieval fortification has weathered the centuries better than any other structure from its era.

A Spanish forest is filled with mysterious stone carvings.

A lone cannonball remains lodged in the walls of the Hotel de Sens as a sober reminder of a revolution.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A Romanesque tower appears when water levels drop.

The world's largest solar furnace uses 10,000 mirrors to concentrate the sun's rays to generate power.

Wonderland replication in progress by one persistent man.

A darkly erotic open-air statuary in Catalonia.