This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

The first car-centric shopping plaza in the U.S. brought a little bit of Spain to downtown Kansas City.

This elaborate towering structure was once famed for its revolutionary height.

Yo, Adrian!

One of the most powerful religious centers in the Middle Ages, dubbed the founder of Western monasticism.

Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.

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

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

Site of a classic 19th-century physics experiment to prove the earth is rotating.

The celebrated eyesore created by starry-eyed sweethearts.

Romania's triumphal arch looks out over Bucharest.

17th century palace once a meeting place for politicians.

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

Romania's only crater lake with water as pure as if distilled.

The ancient Greek Titan guards this massive dam holding a lightning bolt to symbolize electricity.

No one knows who built this strange cave of worship or exactly why.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

Gigantic Romanian salt mines used to heal respiratory conditions.