This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

Rustic natural hot springs in the deciduous rain forest.

A marvel of Byzantine engineering under the streets of Istanbul.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Peek through a transparent pyramid and drink in the mountain made of books.

Hear the quietest sound from across the dome.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

One of only two commuter aerial tramways in the United States.

Historic funicular railway, believed to be the shortest railroad in the world.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

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

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

Eons old volcanic activity created one of the most stunning rock formations in the United States.

The largest self-built castle in the U.S., six decades in the making.

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

Started as a kitchen garden, now the second largest botanical garden in the world.

Oregon's unexpected high desert, displaying layers of time in a colorful show.

A bizarre roadside attraction and the first instance of miniature golf in the world.

One of the largest, oldest, darkest, quietest motel rooms in the world.

Experience a quartz crystal sound bath inside a storied, all-wood sound-chamber.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

Roman ruins top white travertine terraces formed by ancient hot springs.