The oldest standing structure in downtown San Diego.

This historic Chinese church was relocated and revived as a museum that preserves and celebrates Chinese art, history, and culture.

North America's largest accredited model railroad museum.

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

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

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

An inconspicuous footbridge beloved by San Diego locals.

A couple turned their front yard into an artistic masterpiece.

This San Diego museum, housed in a former Navy training facility, is dedicated to preserving women’s historic achievements.

Folklore says this medieval fortress was plopped atop a portal to hell to trap the demons below.

A cave network located at the southernmost tip of mainland Greece was once believed to be an entrance to Hades.

According to one local tradition, the entrance to the Voodoo underworld can be found in New Orleans through seven gates scattered throughout the city's French Quarter.

An unfortunate geological resemblance to Satan has labeled this Pasadena gorge as a passage to the underworld.

A deadly ancient portal to the underworld.

These azure waters were thought to lead to the Mayan Underworld.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Virgil's many-mouthed gateway to the underworld.

Hellam Township is reputed to feature seven remote gates, which when passed through in the right order, open an entrance to hell.

Native Americans built this circle of stones, which was used to predict astronomical events.

A gap in the concrete has been transformed into a miniature playground for the mind.

This mysterious series of teeny guerrilla installations sheds a whimsical light on street art in Oakland.

Julia Morgan's Moorish-Gothic labyrinth of fountains, trees, natural light and Oakland's notable dead.

A temple devoted to inner esoteric mysteries located in a California commercial strip.

Spiral labyrinth hidden in the hills above Oakland, CA.