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

This saltwater swimming pool, which is the last of its kind in the United States, is slowly crumbling within sight of multiple high-end beachside hotels.

Hawaii’s largest cemetery rests inside an extinct volcano crater.

On Waikīkī Beach, a monument to four extraordinary individuals of dual male and female spirits who brought the healing arts from Tahiti to Hawai'i.

A lone traffic cone perched on a ledge has remained unmoved since at least 2011, unofficially earning the status of a tiny Chicago landmark.

A dazzling work by a Pop art legend hangs in one of the world’s busiest subway stations.

Louis Sullivan’s dark, swirling cast-iron designs envelop a popular department store in this Chicago landmark.

This overlooked courtyard and museum celebrate Benjamin Franklin's life and achievements.

Trace the history of the nation’s early days at the site of America’s oldest stock exchange.

Over several decades, one of London’s most iconic city gates was dismantled, moved out of the city, and then moved back.

One of London's lost rivers runs through a pipe over the tracks of this subway station.

A living memorial to the trees London lost during the Great Storm of 1987.

The bones of two medieval royal lions were discovered at the historic fortress.

The medieval woodcut-style artwork chronicles life in medieval London.

Legend says these colorful, invasive residents are the descendants of birds released by Jimi Hendrix.

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

At the top of the hour, figures of the London department store's two co-founders emerge and bow to each other.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

England's oldest surviving hedge maze has been confusing visitors for over 300 years.

Carved initials which are nearly 500 years old preserve the deposed Queen's presence at Hampton Court Palace.

In 2013, historians discovered a hidden room devoted to the art of making royals' hot chocolate.

A quartet of tiled art pieces adorn the floors of this prestigious art museum.

Soon after its unveiling, this giant inverted globe sparked controversy and was vandalized.

A cluttered and astounding collection of antiquities and curiosities.