Super-heavy Nazi architectural experiment.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

A towering monument to war, located on a beautifully peaceful hill.

Berlin's old airport.

Tiny memorials honor individual victims of the Holocaust.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

A monument to the man who almost killed Hitler.

Hundreds of small crosses have been carved into the bark of the trees outside this small Estonian village.

The mile-long pier stretches from a ruined fortress out into the Baltic.

This ornate church has survived Nazi and Soviet occupation, including a short stint as a Soviet-era gymnasium and cinema.

These crumbling Latvian forts make for some haunting seaside ruins.

Mysterious heaps of stones dot these otherworldly woods.

A statue built to honor the elite soldiers who fought for Latvia during World War I.

With a design inspired by traditional Latvian textiles, this monument honors the Latvian people who suffered under Soviet occupation.

A monument to the grand synagogue that stood in this space before Nazis burned it down.

A meandering boardwalk across the bogland leads to a "stairway to heaven" with sublime views.

This World War II relic let Allied pilots know they were entering neutral airspace.

This 30-foot pile of rocks may be the grave of a mythological Irish queen.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

A guitar mounted on a wall in Temple Bar honors the Irish musician.

The oldest public library in Ireland.

Originally commissioned as a sculpture to reflect the history of Belfast's red-light district, the final sculpture has been banned from Belfast public land.

A series of stained glass artworks that depict images of the hit TV show.

These engineering masterpieces are a dominant feature of the Belfast skyline.