A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.

The little-known second castle that William the Conqueror built in York.

A typographic tribute to the many comedic greats who make Great Britain laugh.

This iconic 1,000-year-old medieval castle is a favorite of the film industry, most notably as the location for Hogwarts in Harry Potter.

The largest cave chamber in Britain—big enough to fit a whole cathedral inside.

These legendary stone steps were once used to haul coffins up the rockface.

A 30-acre garden inspired by the principles of modern physics.

The smallest pub in Britain was once a cabinet of curiosities and it still has the dead cat to prove it.

A decommissioned tube carriage within a London museum hosts a regular pop-up supper club.

This giant wooden treehouse within a sprawling garden has its own eatery.

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

An impressive Neolithic henge with banks nearly 10 feet high.

The fountain marks the area where hundreds of accused witches were burned at the stake.

The final resting place of soldiers' loyal canine companions.

Many of Edinburgh's more unsavory characters spent their final days behind this door while awaiting their executions.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.