An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Housing the famous Norwegian ice-defying 19th century polar exploration ship.

Across the Pacific in a raft, a museum dedicated to Thor Heyerdahl's now legendary expedition.

Hidden in an ordinary Midtown building is a one-room museum dedicated to the greatest escape artist.

This Masonic lodge was the first major private building to be constructed in Washington, D.C. after the Civil War.

This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

Designed to not only to represent the history of the local community but also, the future.

The museum is housed inside the historic 1863 Carson City Mint.

Two well-preserved charcoal kilns survive in a remote part of eastern Nevada.

The helicopter that "Tricky Dick" absconded from the White House in on his last day in office.

This pole near the infield rail at Belmont Park marks the jaw-dropping margin of Secretariat’s 1973 Belmont Stakes victory.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

A hidden courtyard houses early 20th-century plaster masterpieces.

An unexpected connection to Chicago awaits visitors on an island just off the California coast.

The site of the largest mass execution in Rhode Island history, haunted by the ghosts of hanged pirates.

This settlement on the original Transcontinental Railroad began by harvesting timber, but transitioned to a forgotten 19th-century industry: harvesting ice.

At this studio, musicians, engineers, and quite possibly a music-loving ghost carry on Puerto Rico's musical traditions.

These markers are used to document elevation changes around the famed dam.

Unusual white sandstone formations in the Los Padres National Forest.

Located close to a movie studio lot, this restaurant has a long history of star-studded patronage.

This mile marker stands at the unofficial end of a highway built to defend the United States from a Japanese invasion during World War II.

The former home of Lillian Evans Tibbs and her grandson, Thurlow Evans Tibbs Jr., whose prodigious contributions to music and art spanned more than 90 years.

A 30-mile-long glacially-carved canyon leads to a massive pair of glaciers.

The unique location where the former president was rapidly sworn in.