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

A bit of retro transportation flair preserved in the world's largest department store.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Eighty million natural history specimens call this gargantuan museum home.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

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

One part local history, 99 parts gruesome haunted house.

The longest hedge maze in the world.

Famously misunderstood wonder of the ancient world

An isolated 17th-century chapel on a remarkable site once dedicated to Celtic sun worship.

The highest peak in Wales is said to be the final resting place of a giant killed by King Arthur.

The stately remains of Llywelyn the Great's mighty fortress.

This historic franken-chapel is the oldest wooden church in the world, at least part of it.

The biggest and deepest Cold War bunker open to the public can be found in southeast England.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

Museum about life, death, and cannibalism in the Stone Age.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

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

400-year-old garden, restored to beauty.

A disastrous D-Day rehearsal was relatively unknown until this sunken tank was discovered 40 years later.

The abandoned fishing village was swept right into the sea.

Take a sea tractor to the Art Deco hotel on the island that inspired Agatha Christie.