The shell of a medieval fortress offers commanding views of the area it once protected.

Each year melting snow turns these Austrian hiking trails into scuba zones.

An industrial site turned into Hungary's most cherished natural wonder.

Hungarian self-built castle.

This oddly shaped building is a surprising Soviet-era crematorium.

The abandoned "Red Star Train Graveyard" is the final rusting place for precious artifacts of train history.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

This attraction was abandoned after the Chernobyl disaster.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

When you've got to go, you've got to go.

Started as a kitchen garden, now the second largest botanical garden in the world.

The oldest known university in the world is in Fez, Morocco.

An eerie former warehouse turned cistern turned movie set.

The remains of a magnificent medieval fortress that was the capital of a vast empire.

An awe-inspiring mosque in Morocco with one of the tallest minarets in the world.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

A forgotten and crumbling Yugoslav monument to the victims of fascism.

This huge metal monument is slowly being stripped to its concrete skeleton.

A massive 1830s industrial site once known as Czechia's "Iron Heart" has been transformed into a playground of science, technology, and art.

Budapest's Communist-era statues, banished to the suburbs.

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

A slice of central Asia in the middle of Berlin.

An eerie, derelict amusement park in Berlin.

A collection of abandoned typographic signs from Berlin and beyond.