The first tunnel to be dug beneath a river, repurposed as an art and museum space.

The remains of an ancient Roman teenager are memorialized at the base of a modern London landmark.

One of the world's oldest trees comes with a Welsh legend intertwining it with a spirit prophesying death.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

You'd never know the houses at 23-24 Leinster Gardens were fakes—until you see the train tracks on the other side.

This silent sentry in the crypt below a large Gothic cathedral is often knee-deep in water.

The pioneer of psychoanalysis spent the final year of his life here, still seeing patients on that famous couch.

Now nearly dry, this lake is said to be the ancient home of the Lady of the Lake, and was once thought to be bottomless.

A magnificent Victorian garden that brings the charm and style of old-time aristocracy to the 21st century public.

This 15th century pub is one of only two pubs in England situated on consecrated ground.

This shell of a historic manor house on the Isle of Wight is said to be the most haunted site on the island.

This hidden green space is the city's second largest conservatory.

Luxurious hotel designed to stir the imagination of its many visitors.

Rare collection of medieval books under lock and key.

Built by the patron saint of illusionists this Elizabethan manor house is riddled with secret cubbies for hiding priests.

Europe's largest prehistoric mound – burial site of a legendary king?

Sometimes an island, sometimes a rocky outcropping connected to the world by a tiny suspension bridge.

Art Deco and “Wrenaissance” mash-up, this recently restored royal residence has been home to kings and comes with secret monkey passages included.

Grotto replete with mystical designs laid out in glued shell mosaics.

The curious and tiny collection contains some very odd objects.

This huge concrete map of Scotland was built as a thank you gift from a Polish soldier.

Macbeth's infamous "Great Birnam Wood."

A perilous medieval road leading right into the sea.

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