A Nesting Doll of Churches.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

Gargantuan home of Russian science.

Stalinist skyscraper built with help of cryotechnology.

World's largest bell sits on the grounds of the Kremlin in Moscow.

Former headquarters of the KGB.

A sculpture park of the tossed aside relics of the USSR, from Stalin to a massive Soviet emblem.

The haunting complex honors the millions of Ukrainians who died in the forced famine under Soviet rule.

This 1000 year old relic-filled cave monastery and UNESCO World Heritage Site also hosts an amazing micro-miniature museum.

An Art Nouveau building covered in animal gargoyles and grotesques.

The deepest metro station in the world.

340-foot statue built to honour the Heroes of the Soviet Union.

This unassuming museum's slogan translates to “there is a limit of sadness, anxiety has no limits."

A statue in Budapest's Liberty Square honors the former U.S. president's efforts to end the Cold War.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Once the home of a hermetic monk, this cave now houses a small church.

A musical instrument played by the sea.

Where the lovelorn find a home for their sentimental keepsakes.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

One of downtown Berlin's last reminders of its Communist past.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

Cold war icon and onetime "hole" in the iron curtain.