A once celebrated industrial wonder now lurks in a quiet corner of Flathead Lake.

The final home of the most famous horse of the American Civil War.

This elaborate High Victorian Gothic structure is one of the world's few 16-sided buildings.

This giant meditative chakra sits peacefully in the Flathead Valley of western Montana.

This is the oldest Roman-made bridge in the city still existing in its original state.

Conflicting markers on its floor tell a tale of two city centers in San Antonio.

Legend has it the commander of the defenders drew a fateful line in the dirt with his sword just before the final battle.

A gorgeous garden oasis with winding paths, stone bridges, and a troubling history.

In 1958, an MIT fraternity pledge laid down on this bridge and instituted a new, unique unit of measurement.

One of Frank Lloyd Wright's greatest—and favorite—architectural masterpieces was almost lost.

A modern zoetrope on the New York City subway.

The blinking light atop the iconic landmark has been sending secret messages for decades.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

This tower commemorates the spot where George Washington hoisted the Grand Union flag.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

Rhode Island's tallest building bears a resemblance to the "Daily Planet" building and has been empty for more than five years.

The place where Samuel "Slater the Traitor" brought the Industrial Revolution to America.

The first ever diner included on the National Register of Historic Places is famous for its custard French toast.

One of the world's earliest skyscrapers.

Mysterious rocks that ring musically when struck.

The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

This amazingly preserved Gold Rush town is a historian's dream.

This subterranean oyster house has been the pearl of Grand Central Station since 1913.