A marvel of Byzantine engineering under the streets of Istanbul.

Roman ruins top white travertine terraces formed by ancient hot springs.

On this romantic tidal island reachable only at low tide the tomb of a famous French writer overlooks the sea.

An image of the legendary saint stands in the shadow of a cathedral she liberated.

This enormous "cloth of the conquest" depicts the Norman invasion of England in mind-blowing detail.

Remains of the artificial harbours invented for the Allied invasion of Normandy can still be seen at sea.

The largest crypt ever constructed in France was built in the 11th century on an ancient Druid sacred site.

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

Hundreds of prehistoric stones, arranged in perfect lines in a French field.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

The famous winding walk at Chartres is surrounded in mystery and myth.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

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

19th century pendulum and a clock restored by a rogue group of guerilla artists.

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

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This medieval tower is all that remains of the castle where Joan of Arc was held before being burned at the stake.

The world's largest piece of copyrighted artwork.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

Mrs. Mallard and her brood are a beloved fixture in Boston Public Garden.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

Two thousand artifacts from around the world collected by one woman who loved to travel.

An enormous, inside-out glass globe built in 1935.