The ruins of an 11th-century Norman castle with a rare, perfectly circular shape.

A musical composition 1000 years in length plays at the Trinity Buoy Wharf in London.

Public access to clean drinking water was an instant hit among the masses.

Old-fashioned knowledge and modern engineering create the world's only rotating boatlift.

Dating back almost 400 years, the oldest public collection library in the United Kingdom was once the study hall of Karl Marx.

This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

This London plaque marks the spot where David Bowie's famous alien made his debut.

This Scottish bridge seems to compel dogs to leap to their death.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

A clock designed to run with perfect accuracy for 10,000 years.

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

London's old-school healing garden.

Scattered throughout London are ancient remnants of the city's former bounding wall.

The largest greenhouse in the world is home to over one million types of plants.

This 1920s Dutch barge is now a floating bookstore.

A unique waterfall that some believe attracts the fairfolk.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

Remnants of a Victorian garden feature sitting in public woodland.

A strange rock with a sinister reputation lurks within the crimson waters of this Scottish glen.

Hear the quietest sound from across the dome.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.