A marvel of Byzantine engineering under the streets of Istanbul.

The glowing blue Nymphaeum of Emperor Tiberius.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Erotic art covers the walls of the largest ancient pleasure palace.

Virgil's many-mouthed gateway to the underworld.

Italy's third-largest Roman arena gives a peek into the underground operations beneath the ancient spectacles.

A sulfuric hellscape in southern Italy.

Pompeii's less famous neighbor is still revealing her secrets.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

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

This Oakland fairytale kingdom, fiercely devoted to childlike whimsy, was an early inspiration for Disneyland.

A massive ultra-modern church presents a science-fiction view of Catholicism's inclusive future.

Oakland's beautiful monumental cemetery.

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