A hidden three-foot-wide house separates these two regal churches.

An enormous, inside-out glass globe built in 1935.

One of the now-less-hidden floral gems of the "Emerald Necklace."

This coffee shop lies hidden beneath a historic church.

London's smallest police station is barely the size of a phone booth.

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

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Countless stories attempt to explain Poland's mysterious J-shaped trees.

Ever-changing museum dedicated to graffiti and contemporary street art.

A socialist building dedicated to teachers showcases one of the largest Soviet mosaics in the world.

One of downtown Berlin's last reminders of its Communist past.

An astonishingly accurate water clock that doubles as an hourly spectacle in this Berlin shopping area.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.

A fascinating insight into daily life in the Eastern Bloc.

One of the oldest cemeteries in Germany was originally used for victims of a cholera epidemic.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

Dedicated to the explorer who opened Japan to the West.

The ruins of one of the first railroads in the U.S. lie hidden within a neighborhood cul-de-sac.

The most confusing clock in New York.

One of the last remaining World War II Victory Gardens in the U.S. is quietly growing across from Fenway Park.

A trompe-l'oeil statue honoring the first guide dog in North America.