While many places make the claim, the Library of Congress says this restaurant is the birthplace of the hamburger.

137 graves holding New England's earliest residents.

One of America's oldest private membership libraries was long one of New Haven's best kept secrets.

More gold than anywhere else, ever.

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

Visible below the waves are memorials to the city's Gold Rush dead.

Once the main gateway to Tokyo, sneaking through this checkpoint was a capital offense in feudal times.

Birthplace of the Tendai sect and home to the marathon monks.

This ancient shrine has been rebuilt every 20 years since the eighth century.

The iconic castle that withstood a magnitude 6.2 earthquake has become a symbol of resilience.

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

Longtime headquarters of controversial boys' club for the world's wealthiest and most powerful.

A 140-year-old castle with underground caves hidden in San Francisco.

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

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

A glamorous hotel that once accommodated French resistance fighters and concentration camp survivors.

A memorial to the soldiers who died in the bloody battles to control Verdun in World War I.

Before the electric telegraph, a chain of stone towers carried messages across France.

One of the most powerful religious centers in the Middle Ages, dubbed the founder of Western monasticism.

Tables of secondhand books fill the inner courtyard of this 17th-century stock exchange.

This crumbling, graffiti-covered mansion sits tantalizingly within reach of the proletariat who frequent a public park.