These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This building has a giant piercing through one of its corners.

This fountain is dedicated to the workers who perished constructing the Fréjus Rail Tunnel.

When this funny little building went up in the 19th century, most people thought it would simply fall over.

One of the few remaining temples of the Religion of Humanity.

This small Roman arch was transformed into a dwelling by the founder of the Trinitarian Order.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

The train platform where Jews were sent to concentration camps is now preserved as a Holocaust memorial.

One of the oldest and most significant collections of Ancient Egyptian archeology outside of Egypt.

The intricate geometry inside this Baroque-style dome was designed to create "terror of the human soul."

Six paintings reminding you that death is integral part of everyday life.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

Built on a medieval synagogue, this church has a burial crypt, tunnel system, and Jewish ritual bath hiding deep underneath.

Italian cave with exceptional acoustics and an unsavory history.

A mysterious ancient elephant said to possess magic powers is now the symbol of a Sicilian city.

The world's most active stratovolcano is almost always erupting.