A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

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.

This striking sculpture of Icarus honors Greece's fallen flyers.

The ruined doorway is a portal to the building's turbulent and torturous past.

A sharp sculpture made of thousands of pieces of jagged glass.

This ancient hydrological marvel is now the base of a modern outdoor cinema.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

This gem is often wrongly overshadowed by the larger, newer Metropolis church in Athens.

Where commuters walk through remnants of an ancient Greek necropolis.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

There has been an astronomical clock on this spot since the 14th century.

This 14th century wine cellar is home to the oldest barrel-stored wine in the world.

This museum tells the story of lake dwellers from 4000 BC to 850 BC, replete with stilt houses and goats.

Among the ostentatious rococo ornamentation of this church, an image of death cuts the life-thread.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

The summit Roosevelt conquered before he descended to become The Chief.

Forget Hollywood, one of the biggest stars in the world can be found in Roanoke, Virginia.

A 13,000-year-old mastodon skeleton was found during the construction of a 19th-century New York mill.

The first American home of the isolated, egalitarian religion has a trove of Shaker architecture and artifacts.

This giant monument of the RCA mascot is a beloved fixture in Albany, New York.