Ruins of a 13th-century fortress perched above a breathtaking Mediterranean bay.

An islet filled with wooden houses where the open sea meets a lagoon.

A seaside castle complex that stood through centuries of conquests.

The remains of a military communications outpost still stand on this Greek island.

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

Giant topiary dog once played a role in a terrorist bomb plot.

This former limestone quarry is now a subterranean wonderland of grand stonework.

Abandoned blockhouses from Nazi Germany's Atlantic Wall erode into the sea on a French beach.

A somewhat mysterious biomedical museum housed inside a Spanish university.

Stormy conditions send jets of seawater bursting through holes in the cliffs.

A deer-headed statue that brings together a 12th-century legend and big wave surfing.

An eerie, derelict amusement park in Berlin.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

Perhaps the most spectacular grotto along the Algarve coastline.

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

This small chapel is built of human bones and decorated with a golden skeleton.

This church sits upon a peaceful hill and a long, turbulent history.