The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Fascinating exhibits of prehistoric and ancient artifacts displayed with a uniquely modern touch.

A well-restored ancient archaeology site gives a real feel for life during the Roman age.

Tiny memorials honor individual victims of the Holocaust.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

Hans Christian Andersen for the postmodern world.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

The gilded, masterful astronomical clock will calculate time, dates, and planetary positions for thousands of years to come.

A brush maker used his factory to protect blind Jews from the Gestapo.

One of the world's oldest universities houses an incredible collection of anatomical models, mummified body parts, and human bones.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

This funky former tobacco factory is one of the most striking examples of Madrid's cultural diversity.

Shrapnel, dynamite, bullets and Franco couldn't destroy this bust, rescued and kept hidden as a family secret for over 40 years.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Over the centuries, this island paradise has done it all, from providing monks with ecclesiastical respite to sheltering an exiled Leon Trotsky.

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Whether they are bulls or pigs, these ancient animal sculptures are fascinating relics.

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

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

Earth's rocky history has rarely glittered so brightly as it does in this Spanish museum.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.