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

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

Mysterious lost empire of the Silk Road.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

The largest Neolithic ruins in the world hide a notably clean prehistoric metropolis.

Naturally protected city carved from a rock face.

Believed to have once stored either human remains or rice wine, thousands of mysterious stone jars lie in ruin.

This Vietnamese hell cave lets visitors take a walk through a devilish underworld full of demons.

A quick and simple solution to Cambodia's train woes.

This impressive clifftop temple was once at the center of an international custody dispute.

This Cambodian riverbed is covered in ancient Hindu carvings both above and below the waters.

Experience architect Le Corbusier's modernist design for living in the home he designed for himself.

Abandoned railway line circling the city of Paris.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

A Belle Epoque bordello turned into a themed love hotel.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

Indents in the pavement are all that remain from a grisly death machine in Paris.

Paris' fabled purveyor of exotic taxidermy and natural history curios.

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

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