One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

The topiary maze at the Habsburg hunting lodge.

The Habsburgs' royal collections of art and wonders.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

Baroque celebration of the end of the Great Plague of Vienna.

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

The mummified right fist of a 1,000-year-old saint-king sits inside an ornate golden reliquary.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

A giant portrait of an ancient king looms over the river.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

A Roman monument to their own civil engineering prowess.

Romania's triumphal arch looks out over Bucharest.

Ancient serpentine sacrifice holder that has stood the test of time.

1513 Turkish world map, full of European state secrets and snarky commentary.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

A misnamed well, with a deep dark past.

A former major munitions plant that has been converted into a sprawling art space.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

Home to items never before seen by the public.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

The "lovely red Vega" of the legendary record-settling pilot.

At 207 feet, one of the world's longest continuous escalators.

The site of the climactic scene from the classic horror film is now a historic landmark.