Jesus' footprints and the first catacombs in the world.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Architectural monsters are devouring this palace's every door and window.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

The final resting place of the poets Shelley and Keats.

2300-year-old Roman road connecting the empire.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The underground sanctuary of a mysterious ancient cult.

An alchemist's "magic door" stands in the middle of a Roman park.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

Architectureal fantasy quarter of Rome.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Abandoned bridge hidden deep in the San Gabriel Mountains.

A shockingly detailed small scale recreation of the temples of Abu Simbel.

Named after a bandit and the star of several Hollywood prehistoric landscapes, these sandstone formations are a historical part of the Los Angeles natural landscape.

A non-native grove of 241 redwoods in Southern California.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

Remains of a Greek freighter trapped off of Rocky Point in 1961.

The 10-foot-wide Long Beach home was built on a dare.

The creator of the carousel's bingo-pinball hybrid survives in California's oldest gaming establishment.

About 80% of all U.S. avocados are descendants of Rudolph Hass's glorious tree.