A restaurant and observation deck built in a unique broadcasting antenna.

A cluster of historic bathhouses built on the famed hot springs that gave the Georgian capital its name.

This neon lit Georgian cave claims to hold the boulder Prometheus was chained to.

The first skyscraper to include a Ferris wheel built into the facade.

A subterranean house of worship carved right out of the bedrock.

Estonia's largest creative city is a vibrant bohemian hub located within a former industrial complex.

The first museum in the world devoted to sexual gadgetry.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

An ancient knight and a symbol of the city's freedom.

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

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

When a supermarket opened up shop within a medieval building it became protected by UNESCO on a technicality.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

The only gulag ever to exist in socialist Yugoslavia.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

The now-overgrown beach resort was once frequented by Yugoslav military elite.

This picturesque medieval monastery guards a small trove of historic treasures.

Longest fortress system anywhere in Europe.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

Yugoslavia's biggest underground airport lies in ruins.

A striking symbol of the Bulgarian capital.

The first mosque in the world to receive electricity.

An apparition of Virgin Mary in Herzegovina.

Controversial site of what could be Europe's first pyramid.