This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

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

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

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

Rare karst landscape eroded from a flat seabed.

A careful eye can find hundreds of dinosaur tracks running along the Connecticut River.

The walkable ruins of an 19th century hotel, destroyed in a horse cremation gone wrong.