Britain’s longest ancient monument, this great 8th century earthwork was built to mark the boundary between what would become England and Wales.

This ancient altar emerges from the thick forests to reveal the mysteries of Etruscan sacrificial rituals.

You can crawl inside this atmospheric 5,000-year-old tomb.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

A swath of France so devastated by war it is still forbidden to go there.

This gigantic monument hidden in the woods was built to thank the Dutch for sheltering Belgian refugees during World War I.

An abandoned tower once used to study the cosmos hides within a thicket of greenery.

A miniature Italianate fantasy village on the coast of Wales and the set of ITC classic "The Prisoner."

This Roman amphitheater is said to be King Arthur's legendary Round Table.

The real life Hobbiton, this sheep farm has been forever transformed since being built for The Hobbit film series.

In the ancient Woolley Woods, an art project promises access to new worlds.

A secluded natural oasis hidden deep along a rainforest trail.

Now abandoned, this stone church was part of the missionary efforts that initiated the Christianization of Zambia.

A historic cave in Scotland once served as a hiding place for a famous Covenanter.

Medieval ruins on a tiny island amid a flooded lake offer romantic respite to lovers seeking privacy.

Croatia's "hairy stone" fortress is one of the most well preserved Istrian castles.

The medieval-looking hammer beam teak roof may be a Victorian vanity, but it's still absolutely magnificent.

This ruined medieval castle was the scene of Lord Robert Dudley’s seductive reception for Queen Elizabeth I.

The castle still holds traces of the abandoned Roman fort it was built atop.

This early Norman castle was the first historical monument protected by an act of Parliament.

The oldest still-inhabited hill fort in India looks like a magnificent golden sandcastle.

These crumbling foundations are all that remain of the once-stately 1840s manor that gave the town of Bradenton its name.

A mysterious pillar in an ancient burial chamber is said to predict how long you have to live.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.