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

2300-year-old Roman road connecting the empire.

The haunting ruins of Jack London's dream house.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

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

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Neoclassical Revival mansion and set of horror cult classic Phantasm.

An "anarchical" no man's land, complete with garbage sculptures and a hobo-run "Landfillian Library."

The memorial to the victims of the Jonestown Massacre carries the names of 918 lost, including one name people wish wasn't there.

A playground built by the kids that is a child's wonderland, and a helicopter parent's nightmare.

A shape-shifting buy-sell-trade bookstore, born to Beatnik Era spirit.

Oakland's beautiful monumental cemetery.