The ancient mosaics here are considered among the finest in the world, and serve as a stunning record of Greco-Roman daily life.

A marvel of Byzantine engineering under the streets of Istanbul.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This pink watchtower served as the seat of the Greek government after independence from the Turks.

This famous archeological mystery may be an ancient example of movable type.

A minotaur, a labyrinth, and a dubious restoration pull in visitors from around the world.

This open air archeological site houses almost as much wildlife as it does classical religious artifacts.

17th century palace once a meeting place for politicians.

It took 40 years to build this Eden-like garden in Marrakech, later restored by Yves Saint-Laurent.

A Turkish ghost town abandoned in a population exchange with Greece.

Monasteries on rock pillars, once accessible only by frayed ropes.

Abandoned railway line circling the city of Paris.

France's most famous cemetery, with some of its most curious tombs.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

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

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

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

A muddy alien landscape that is home to rare species of exotic plants.

Conspiracy theories and occult legends surround this mysterious natural rock formation.

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).

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.