Guests can stay at a hotel in the former French abbey where lie the tombs of King Henry II and King Richard the Lionheart.

A subterranean shelter remains intact under a busy Paris railway station.

This museum in a Paris apartment gives a unique look at the iconic French singer's life.

Ivy-covered Medieval tunnels cut through this charming town in France's Loire Valley.

Museum on French naval history, with magnificent figureheads, a historic diving suit, and a boat used by Napoleon.

A modern-day Lascaux cave underneath Paris.

The curious underground history of keeping Paris clean.

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

A French artist's vague warning hangs over Belleville.

What looks like a normal building is really a hollow facade hiding a subway vent.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.