Architectural monsters are devouring this palace's every door and window.

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

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

Jesus' footprints and the first catacombs in the world.

The underground sanctuary of a mysterious ancient cult.

An enigmatic modern marker left next to a historic Roman site.

This bridge was constructed from the rubble of the infamous Bastille.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

One of the largest underground systems runs under Canada's largest urban center.

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

This bar named after the world's first mixed cocktail was home to one of New Orleans' most notorious politicians.

Sleep where gangsters fell amidst smoke and flame, with nary a bullethole to show for the legendary struggle.

The real faces of Venice beach captured on Romanesque columns.

This subtle Berkeley paving stone actually marks off a lawless tube of air that extends into space.

Wild West history in Hollywood style.

Barely visible foundations remain where Stow Lake’s “observatory” once welcomed visitors.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

The oldest burial ground in the city, final resting place of city founders, Ohlone natives and murderers alike.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.