Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

This desert oddity hides in plain sight thanks to a cartographic error and a desert explorer with a punny sense of humor.

This cave was hidden for thousands of years, storing the worldly goods of ancient Native Americans.

Every spring, locals see the shadowy figures of a ghost army of slain Greek soldiers descend upon this ruined fort.

This stone tower was built to protect Crete from incoming pirates.

An extraordinarily ornate museum in San Diego holds wondrous anthropological treasures.

The world's largest outdoor organ is played weekly by one of just two civic organists in the U.S.

North America's largest accredited model railroad museum.

Swarms of butterflies cannot compare to the awe inspired by the publicly-funded nakedness once displayed in this sunken garden.

Built for an exposition in 1915, these horticultural displays have stood the test of time.

A hidden courtyard houses early 20th-century plaster masterpieces.

One of the largest trees of its kind in California.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

This old mining town, deep in the California desert, has a year-round population of one.

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

This demon atop the Notre-Dame de Paris looks utterly bored.

This modest marker near Notre Dame identifies the very center of Paris.

This scenic fortress dates back at least 2,400 years to the time of Magna Graecia.

A minotaur, a labyrinth, and a dubious restoration pull in visitors from around the world.

Monkeys inhabit the lush forest surrounding ancient Mayan ruins once considered sacred.

Deep in the Guatemalan jungle stands an ancient pyramid that once marked the reign of a king.

This staircase full of Mayan hieroglyphics is perhaps the largest single text in the world.