This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

This historic stone bridge has an entire neighborhood clinging to its sides.

This historical Netherlands fortress still bears the marks of its single siege.

Underneath the city that invented pilsners are a series of historic tunnels that have been storing beer for centuries.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Trick water gardens from 1619 featuring a 200 piece mechanical theater powered by water.

After the famous composer died in Paris, his sister snuck his heart out of the country to honor his wish that it be buried in their native country.

This uber-quaint Polish village is known for its habit of painting elaborate floral motifs on just about everything.

This man-made mound monument was built out of soil from all across the Polish empire.

Tiring of digging out the door to this church for every service, it was eventually abandoned to the sands.

An ultra-modern diversity park in Denmark has turned an entire city block electric pink.

Boats must transform into railroad cars to navigate this Polish canal.

It's always summer at the beach inside this former airship hangar.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.