Henry VIII's forgotten castle was built by the gunpowder-obsessed king to be defended solely by cannons.

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

This lab's maddening silence is good for business but bad for sanity.

The last physical evidence of the Lewis and Clark trail is one of their autographs etched into this giant rock.

Hidden above a drug store on a nondescript corner of Lincoln Heights is a private clubhouse for intrepid explorers.

The Origin of On the Origin of Species.

Stonehenge has nothing on Castlerigg’s views.

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

The largest stone circle in the world has ended up bringing up more questions than it has answered.

The oldest inn in England served brew to the crusaders.

English antique dealers with a taste for the unusual.

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

A fantastic castle rumored to be the birthplace of King Arthur.

This series of Armenian caves held the oldest brain, shoe, and winery in the world.

Right up until the 20th century this network of man-made caves was the biggest village in Eastern Armenia.

This isthmus in the Bahamas narrowly separates the roiling Atlantic from the cool Bight of Eleuthera.

The underground sanctuary of a mysterious ancient Roman religious cult contains an exquisite traditional fresco.

This one-of-a-kind archeological site is home to strange prehistoric ruins, the original use of which is still a mystery.

This elaborate hole in the ground was built as a sacred site for an ancient civilization.

Largest necropolis in the Mediterranean.

An incredible menagerie of more than 3 million taxidermied animals at the oldest science museum in Europe.

Geometry and mystery come together in an epic show of octagonal masonry.

Art and armour fill every inch of this rich kid's Italian villa.