The top of the holy mountain for the ancient Spartans looks like a pyramid—is it man-made or a natural phenomenon?

This room of wonder is full of relics, from knights in armor to rare works of art.

The enchanting home of an eccentric Swedish physicist and author sits in the hills of Anacapri.

This Gothic castle-like portal is a testament to the amazing craftsmanship of the navvies who built the railway tunnel.

Bits and pieces from the ill-fated Donner Party's winter cabins.

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

An idyllic mineral hot springs facility with a more-than checkered past.

The sinister ruins of one of the worst dam failures of the 20th century lie in this astonishing alpine setting.

An ancient yew tree and holy well nestle beside a remarkable 13th-century church.

The spot where Oxford garnered its name was also home to a medieval philosopher and includes a house covered in statues.

The shop where the girl who inspired the beloved character once bought sweets is now a book-themed commercial curiosity.

The weathered grave of a medieval anchoress who walled herself up in a cell attached to a church.

Once one of the largest rooms full of books in the world, this bookstore basement is still a treat for bibliophiles.

An extraordinary collection of scientific instruments - and Einstein's chalkboard - inside the world's oldest purpose built museum building.

Home to the most complete dodo remains known - one head, and one foot.

Ancient Egyptian wigs, South American feather headdresses, a bounty of anthropological artifacts in Oxford.

An absolutely beautiful 200-foot stained glass installation traces the evolution of knowledge.

Where royalty waits in the height of luxury.

This vast collection of smoking pipes from across the world spans centuries.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

Museum preserving torture methods from the past.

A doorless and windowless folly in England that evokes curiosity over its mysterious origins.

The world's largest mineral hot springs is home to a herd of bison, a free public bath house, beautiful mineral formations, and a terrifying swinging bridge.

In an alcove of this historic library, you can find murals painted in the 1930s by an artist who went on to create some of Disney's most iconic animated films.