One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

A beautiful geyser under environmental threat.

The world's most active stratovolcano is almost always erupting.

Italian cave with exceptional acoustics and an unsavory history.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

"Only the devil could play golf here."

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

A fountain standing as a testament to a doomed alliance.

Ancient serpentine sacrifice holder that has stood the test of time.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

Highly spherical boulders on the shores of New Zealand.

New Zealand's epic shrine to all things puzzling.

Dolphins, ancient clams and hundreds of waterfalls make this one of the world's top tourist destinations.

A glacier pocked with ice caves and surrounded by rainforests.

This strange geological landscape erupts with sudden bursts of water.

Major tourist destination known for its bubbling mud-pools and hot thermal springs.

Tubing through a cave lit with glowworms is a magical underground experience.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

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

A succession of eerily contemplative iron figures lead from a Scottish museum to the sea.

A church that bred legends, and served as an inspiration for the Da Vinci Code.