A tribute to the first human in space.

The largest toy museum in Poland showcases Europe's history of childhood.

What was once an underground Nazi city is now Europe's largest bat reserve.

This 13th century Gothic brick castle is the largest in the world by surface area.

This fairytale inspired, warped building houses restaurants, shops, and a radio station.

The silly symbol for an underground protest group is now scattered around the city.

This imposing 20th-century castle was abandoned before it was ever completed.

The final resting place of more than 200,000 people, this is one of the largest cemeteries in Europe.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

A hidden art gallery in an abandoned Warsaw fort.

An underground city of salt.

In the middle of a busy airport, a statue honoring the astronaut who told Houston that Apollo 13 had a problem.

This Chinese-style quartz sundial was saved in its final hour.

The oldest operating cemetery in Denver is the eternal home of some of the Centennial State's most famous residents.

One of the greatest heroes of the Titanic tragedy came from humble beginnings to this beautiful home.

A landscape decorated with enormous skull sculptures.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Of course Salvador Dalí lived in a castle...

A completely underwater art museum sends a stark message about humans' impact on the environment.

One of the largest ossuaries in Spain is packed from floor to ceiling with bones.

This whimsical winery by Antoni Gaudí looks ripped from the pages of a fairytale.

A whimsical garden of outsider art in the Spanish countryside.