A Spiritualist house of worship where believers communicate with the dead in the spirit world.

An overlooked tribute to one of the most important peace deals in American history.

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

This poor little statue is the most vandalized memorial in Washington.

An amazing example of early-20th-century architecture, this church features marble transported from Utah.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

A historic ruin just 20 feet away from a busy highway onramp.

People escaping slavery may have hidden inside a corpse vault.

The beloved, war-tested mascot of a Union regiment graces their battlefield monument.

This ancient market is often referred to as the oldest shopping mall in the world.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

An ancient Roman temple first dedicated to an emperor's wife is now a church.

This is the oldest Roman-made bridge in the city still existing in its original state.

This one-of-a-kind Roman arch is not actually dedicated to the god Janus.

This curious, round temple is the oldest still-standing marble building in Rome.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

The prototype for all Nazi concentration camps.

The largest treasure hoard in Europe is contained in a castle that was bombed out during World War II.

Every hour the doors open to reenact the legend of the heroic mayor who saved his town by drinking a gallon of wine.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

This grisly effigy displays an early Christian martyr who was skinned alive and beheaded.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.