This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

At this rare mosque in Tbilisi, Sunni and Shia Muslims pray side by side.

The charmingly disheveled clock tower of Tbilisi's puppet theater.

This street has over a half-dozen names, all at once.

This unique Lady Liberty is one of the only examples of the figure sitting down.

The eerie burnt-out remains of a prominent building where 30 protestors lost their lives.

World's largest crossword puzzle spans the side of a towerblock, its clues scattered throughout the city.

Longest fortress system anywhere in Europe.

Sofia's legislative center is continuously reinventing itself.

Eastern Bloc nostalgia, anybody?

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

This historic black and white monastery is one of Bulgaria's architectural jewels.

A plaque marks the site directly below the mid-air detonation of the atomic bomb over Hiroshima.

Peace Park and the Atomic Bomb Dome.

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

Legions of Roman soldiers bathed in this ancient spa complex under a Budapest transit station.

Sitting beneath an unremarkable residential building is a museum devoted to classic Pinball.

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

A tribute to an iconic act of defiance from the Croatian War of Independence involving a small car.

A pair of connected skyscrapers form this symbolic gateway.

A beautiful Arctic museum and nature center preserves the culture of the Sámi people.

Visit the monolithic tomb of America's most famous general.

This family driveway also serves as the highest point in Illinois.

Home to the world's largest refracting telescope and the birthplace of modern astrophysics.