These abandoned grain silos and tunnels are an urban exploration dream.

Chicago's largest cemetery is full of beautiful Victorian monuments and more than a few ghost stories.

A haunting statue called "Eternal Silence" has quite the reputation among visitors with active imaginations.

An enormous park-like oasis, full of famous Chicagoans' graves.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

A British Commonwealth cemetery in the heart of Milan, with 421 allied soldiers died during World War II.

The train platform where Jews were sent to concentration camps is now preserved as a Holocaust memorial.

This memorial plaque remembers a strangely shallow maritime disaster known as "Chicago's Titanic."

No one knows how many bodies are in this vault in a Chicago public park.

A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

This alley in downtown Chicago held the bodies of over 600 people after the fateful Iroquois Theatre fire.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Pompeii's less famous neighbor is still revealing her secrets.

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

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

2300-year-old Roman road connecting the empire.

This medieval city gate is now a blend of the past and the modern world.

The remains of the left arm of the levitating philosopher-saint are kept in a 13th-century Neapolitan basilica.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

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

Vast network of air raid tunnels beneath Lombardy's capital.