Hidden well off the beaten path in Catalonia is this crumbling medieval castle that is slowly being covered in graffiti.

Now a pile of ruins and rubble, this was a lovely mountain town as recently as 1960.

Mausoleum and Holy Seat of Antiochus I of Commagene.

This ancient village and its adjoining cemetery have a beautiful history of death and remembrance.

Jurassic theme park in the small town of Erlian.

Siberian ghost town built by gulag prisoners.

A huge communist-era propaganda monument and mural that offers stunning views of the Mongolian capital.

A memorial to the murdered Jews of Kaunas.

Sculpture garden of religious statues made it through Soviet rule.

An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

Spend the night in 1920s Latvia in this historic recreation and movie set.

One of the largest museums in Ukraine remembers the story of the German-Soviet War in iconic, brutalist style.

A monument to Lenin has been transformed into a statue of everyone's favorite black-helmeted, fool-choking Sith Lord.

This once-grandiose behemoth of a monument from the socialist era now sits quiet and closed up.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

This massive stone and steel monument remembers a century-old battle that cost thousands of lives and nearly destroyed the city.

An abandoned saucer-shaped monument in the Bulgarian mountains.

This Chinese museum proves that it's a watermelon world, we're all just living in it.

The world's largest statue of Mao Zedong looks out over the city where he discovered Communism.

The ancient settlement attracts tourists from all over looking to learn about the Chinese vision of the afterlife.

This abandoned secret city is a crumbling wonderland of Soviet ruins.

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