This tunnel entrance is built to resemble a grand castle but no one is quite sure why.

A Neolithic burial site built 1,000 years before Stonehenge.

Buried for centuries, this hidden cellar is all that remains of London's medieval Whitefriars Monastery.

Classic game cookery takes center stage at what's widely considered London's oldest restaurant.

A mysterious crater-like pond has a spooky tendency to empty and fill with complete disregard to rainfall patterns.

Unusual British home built to disguise a water tower.

The oldest working mechanical clock in the world.

The commemorative stone column conceals a secret laboratory.

A recently restored Shoreditch landmark with ties to Jack the Ripper.

A medieval replica of King Arthur's legendary table, the Round Table hanging in Winchester Castle was decorated by Henry VIII.

Eighteenth-century home, where Herschel discovered the planet Uranus.

The breadfruit-adorned final resting place of the infamous Captain of the HMS Bounty.

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

The 5,000-year-old megalith is believed to be Scotland's tallest standing stone.

The fences outside some of South London's estates are made from recycled World War II stretchers.

England's steepest street has such a drastic incline that locals tie their parked cars to lampposts when it gets icy.

It is still illegal to "quarrel" at this unlikely urban oasis built on top of an electrical substation.

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

An archive of ceramic eggs painted to record clowns' personal makeup designs.

This beautiful deer park was built so King Charles I and his court could go hunting while escaping a deadly plague outbreak.

This Arcadian garden in the Pentland Hills boasts over 270 artworks by Scottish artist and poet, Ian Hamilton Finlay.

This witch statue remembers a time in England's history when fear trumped truth.

This marine reptile was discovered by one of the 19th century's greatest fossil hunters.

A secret door leads to this cozy dive that sells only “milk.”