A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

An out-of-place Air Force radar dome is all that denotes this park as a former missile launch site.

On the side of a Virginia highway, a collection of monuments commemorates an 18th-century trek through the Blue Ridge Mountains.

Dedicated to one of the nation's worst engineering disasters.

This former POW camp was transformed into a Cold War missile installation.

A plaque bearing the names of those who dedicated themselves to protecting Budapest's Jewish population during World War II.

A memorial to the beloved brown bear that served in the Polish army during World War II.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

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

These plaques found across Warsaw commemorate the sites where executions or battles took place during the German occupation.

Once home to some 250,000 volumes and priceless art artifacts, this Polish estate was a target of bombing during World War II.

An artificial date palm stands as a memorial to Warsaw's Jewish community.

In the summer, the area around this sculpture transforms into a vibrant concert venue.

This extensive collection covers thousands of years of Polish military history.

This bell stars in a tragic love tale and is said to make wishes come true.

Special benches that play Chopin's music are scattered throughout his native city.

Legend says this is actually a heartbroken prince waiting for his true love's kiss.

A tree planted by Marie Curie is treasured by the Radium institute that she set up.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

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