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

One of seven Jewish catacombs in Rome and one of only two open to the public.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

Jesus' footprints and the first catacombs in the world.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

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

The final resting place of the poets Shelley and Keats.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

2300-year-old Roman road connecting the empire.

The underground sanctuary of a mysterious ancient cult.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

This taxidermy horse was a Civil War hero.

This statue of the "father of television" stands prominently in the United States Capitol.

After his presidency, George Washington planned to live only a few blocks from the Capitol building.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

A memorial to a shareholder activist feared by CEOs around the United States.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

An ear-piercing buzzer calls lawmakers to a vote with a series of long and short rings to form coded messages.

This grisly headstone doesn’t seem to be resting in peace.

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

‘Bush the old fire dog died of poison July 5th, 1869. RIP.’

A small token of gratitude from freezing cold journalists who were given a warm haven while covering JFK's inauguration.