This unique sanctuary invites you to interact with the beautiful birds.

A crushed gate and giant bronze head serve as a reminder of Greece's fight for freedom.

Large collection from the 3rd millennium BCE.

A sharp sculpture made of thousands of pieces of jagged glass.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

One of Europe's largest supercomputers is housed inside of a disused chapel.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

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.

A beautiful but toxic fountain of mercury.

This semi-secret storybook hedge maze is also the oldest garden in the city.

Dim sum, served in a grand old theater.

A monument park dedicated to the influential Beat Generation author and poet, Jack Kerouac.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

This historic estate on the east shore of Lake Tahoe was home to an eccentric millionaire (and his pet elephant, Mingo).

Reminders of the Battle of Berlin still scar the railway.

These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.

A restaurant and observation deck built in a unique broadcasting antenna.

This World War II bunker now survives as a documentation of the Nazi regime and war crimes.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

A fascinating insight into daily life in the Eastern Bloc.

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

An abandoned NSA listening post on Berlin's "Devil's Mountain."