Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

The names Lúthien and Beren can be found inscribed on the shared grave of the famous writer and his beloved wife and muse.

The world's only international cryptozoology museum is host to an unrivaled collection of mysterious objects.

The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

In an arboretum with hundreds of memorials to the fallen, this one might be the most poignant.

Isaac Newton's former home, where the famous apple tree still stands.

Bonsai trees that are up to a thousand years old.

What was to be the world's most secure Cold War document vault ended up as just a few shallow caves.

A remote hilltop covered in giant monoliths haunts the Brittany countryside.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.