A medieval church with largest and oldest collection of Renaissance frescoes in France.

Hundreds of secret cabinets built into the walls of legendary poisoner's private work room.

Since ancient times these picturesque springs have been providing bathers with healing waters.

An ancient monastery, a locked room, and a mysterious book heist.

Museum in a swimming pool where the water still flows.

One woman's decades-long obsession with the "La Fée Verte."

The narrowest street in Paris.

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

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

Sleep in a climate-controlled plastic bubble for the night.

The oldest and smallest cemetery in Paris is only open to the public twice a year.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

The world's largest reflecting pool is just two centimeters deep.

The artist and his brother are buried in a landscape straight out of a van Gogh painting.

This little-known relic crypt holds stolen parts of a Roman Empress.

Despite being considered a thoroughly American sport, basketball's oldest surviving playing field is found in the basement of a Paris YMCA.

A beautiful and classically designed villa, with an hourly infestation of monsters.

The floorboard scrawling of a tragic madman is on public display outside a Paris hospital, much to the dismay of its opponents.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

A public park off the beaten path with a beautiful waterfall and 13th century Cistercian abbey.

This stunning French estate was so lavish that it landed its original owner in jail for the rest of his life.