This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

Freddie Mercury's childhood home is now a monument to the iconic Queen rockstar.

After sunset the heart of Zanzibar's historic Stone Town neighborhood transforms into a culinary playground.

In Zanzibar, a historic 19th-century palace is a reminder of the world's shortest war.

This monument is a stark reminder of the horrors of the Zanzibar slave trade.

A glass display case holds the document that ended the Second World War—which one person signed on the wrong line.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

A nondescript building that's been functioning as a speakeasy for nearly a century and a half.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

A modest reminder of treacherous waters at the Golden Gate.

A winding path built in secret on the edge of the continent.

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

The unbelievably opulent home built for an infamous newspaperman.

A massive volcanic plug is now a protected area that hosts a number of bird species.

An alley covered with 20 years of bubble gum.

The beautiful behemoth is one of the largest trees of its kind in the United States.

The Los Angeles flood disaster that took 400 lives and ended the career of William Mulholland.

An antique store houses the last operational diner from the defunct department store chain.