Current docking place of the SS United States, the fastest transatlantic ocean liner.

The ruined remains of a coal mining ghost town are hidden within the woods.

Memorializing an American tragedy of massive proportions.

Huge masonic hall in Philadelphia with lavishly themed rooms.

A macabre farm reserved part of its 222-acres for dead bodies, all in the name of science.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

The graffitied ruins stand hidden within the Pennsylvania woods.

Board a mine car and descend the #190 slope 300 feet underground into the Clark Vein of coal.

The legacy of baseball great Roberto Clemente is preserved in a retired Pittsburgh fire station.

This public park was the site of the largest civilian disaster of the Civil War.

A unique workspace where offices reside on pirate ships and inside gingerbread houses.

Long hidden under grime, the politically radical murals of a little known Yugoslavian master are finally getting their due.

The largest clock face in the United States is twice the size of Big Ben and infinitely more ad-sponsored.

Pittsburgh's literal underground railroad.

This spot memorializes one of the greatest plays in NFL history, unless you happen to be a Raiders fan.

The Master of Magnetism dominates the walls of a scrap metal yard to keep graffiti artists at bay.

The world's second-largest sundial, made entirely out of stone.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

Long abandoned underground complex to keep royals safe from a nuclear war that never came.

The "Mystery and Company of Merchant Adventurers" is an Elizabethan-era hangout in Moscow.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

Intricate wood carvings on an island in Siberia.

This newly renovated Soviet-era outdoor exhibition center is bigger than the principality of Monaco.

Former headquarters of the KGB.