2300-year-old Roman road connecting the empire.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

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.

The first AIDS memorial chapel in San Francisco and one of only a few in the U.S.

This private residence was the template for one of the most beloved television homes of all time.

The oldest burial ground in the city, final resting place of city founders, Ohlone natives and murderers alike.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

San Francisco's newly reopened hands-on science museum.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

An artsy hidden staircase leads to breathtaking views of San Francisco.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

One part antique store, one part curiosities hodge-podge.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

Turntable anonymously received orphans, alms, and groceries.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

A beautiful but toxic fountain of mercury.

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.

Where thousands of slaves passed through the "Door of No Return."

This series of rope-style bridges brings visitors into a jungle layer that is usually reserved for birds and monkeys.

This stunning concert hall has become a symbol of Iceland's national recovery.

This tiny museum's sizable collection is jammed into a former underground public toilet.