This "tower of death" has acted as an observatory, a religious hub, and an executioner's lair.

Ancient barriers wrap around what was once an important stop along the Silk Road.

Light still pours into the ruins of this ancient Islamic observatory.

Once a bustling fishing port, this semi-ghost town is now more than 90 miles away from the shore.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

These layered sandstone mountains in China look like they are made of pressed crayons.

A sinkhole and now a swimming hole, too, full of dazzling turquoise water.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

After millennia of erosion by sand and churning water this Brazilian valley now looks like a lunar fantasy.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

Come for the sustainable organic chocolate, stay for the sustainable organic booze.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

This pebble beach is so beautiful that taking its rocks is against the law.

Hidden in a secluded Greek cove is a pristine beach marred only by the rusting smuggler's hulk stranded on its shores.

This black shoreline is made up of exploded lava particles.

Constant erosion has created a surreal landscape of bleached and preserved fallen trees.

Once home to Komodo dragons, this island dreamscape has a rare combination of white, pink, and black sand beaches.

A part of the world's largest marsh seems to be growing bright red Martian grass.

Picturesque intersection of witchcraft and ancient Christianity.

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

Houses are tucked between, on, and underneath giant boulders.