Macabre astrological automaton clock dating to the late 1400s.

A church of bones, decorated with 40,000 human skeletons.

Too much gossip or just missing curfew could land you in here for a couple of days.

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

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

A fountain standing as a testament to a doomed alliance.

A marvel of Byzantine engineering under the streets of Istanbul.

Legend says if you stick your thumb in the hole and it gets wet, your wish will be granted.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

This bridge was constructed from the rubble of the infamous Bastille.

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

Romania's triumphal arch looks out over Bucharest.

This memorial to the victims of the Romanian Revolution of 1989 is often compared to a potato on a skewer.

A striking symbol of the Bulgarian capital.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

A vast Communist-era exhibition space in the Bulgarian capital.

The topiary maze at the Habsburg hunting lodge.

The whole world in one water tank.

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

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

Catacombs turned marketplace.

The rose garden in Regent's Park where Pongo and Perdita met for the first time in Disney's "101 Dalmatians."

Rebuilt remains of a temple to Roman god Mithras.

A 2000-year-old Roman amphitheater lies just below Guildhall Yard.