This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

Italian poet Dante Alighieri is entombed in this small mausoleum in Ravenna, and his hometown of Florence has never been too happy about it.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

Medicinal spa created from the mineral-rich runoff of a geothermal power plant

The oldest private art gallery in all of Hungary.

A fake Transylvanian castle houses a cathedral of antlers.

Late at night, the bust of the "Dracula" actor was snuck onto the facade of this Budapest castle.

Once the home of a hermetic monk, this cave now houses a small church.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A 19th-century artistocrat's mansion, turned into a library, hidden in a modern library.

An eccentric collection of antique items shares space with a prop-quality witchcraft museum.

Moorish signal station on a stratgic rocky outcrop.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

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.

The world's largest wooden structure.

This former charity hospital for elderly clergy houses some of Seville’s most treasured paintings.

A 16th-century Andalusian palace.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

A museum dedicated to the Spanish occult in a town that was terrorized by the Inquisition.

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.

Hidden away in a modern library are the remains of one of the 18th century's most celebrated wunderkammers.