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

This irregularly shaped sea fortress has defended not one but three different sovereign states.

Thirteen sculptures in central Moscow graphically depicting vices of the modern world.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

Romania's triumphal arch looks out over Bucharest.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

The growing stones of Romania.

Religious structure known for its sculpted details.

Something's watching you.

Gigantic Romanian salt mines used to heal respiratory conditions.

This massive underground salt mine now holds a sci-fi theme park in its depths.

Oriental bazaar in the heart of Sarajevo.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

A striking symbol of the Bulgarian capital.

Stone pillars and a petrified wedding party in the hills of North Macedonia.

The elliptical citadel resisted the advance of the mighty Ottomans several times, thanks to the military prowess of the "Dragon of Albania."

The oldest housing complex in Riga is a mini timeline of architectural trends.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

A small part of Russia that does not touch any other part of Russia.

A narrow strip of land is home to the tallest migrating dunes in Europe.

This Ukranian fortress is one of the best-preserved medieval castles in Europe.

The final resting place of soldiers' loyal canine companions.

360° views of the city plus five floors of optical illusions and hands-on science.

"Stairs of the Turks", a chalky white cliff eroded conveniently into stairs, allowing for easy pillaging.