The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

America's smallest national park site is the former residence of exiled Polish national hero Thaddeus Kosciuszko.

South Philadelphia is home to Keith Haring's only surviving in situ collaborative public mural.

The world's third-largest crystal sphere has sat in the Penn Museum since 1927 with the exception of one outlandish theft.

The body of St. John Neumann and his collection of hundreds of relics, on display in a Philly church.

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

A clone-tree in Washington Square Park sprung from seeds that went to the Moon and back.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

The first public building in Savannah to offer air conditioning was a luxurious cinema that still operates today.

An early-19th-century hotel with a past that is steeped in the Civil War.

This kitschy tavern is also home to rare early editions of "Treasure Island."

The former home of Samuel Clemens and family remembers the happiest period of the author's life.

A religious-themed park filled with folk art to bring biblical stories to life that fell into disrepair and now being restored.

This Queens beer hall preserves a German culture and language that is all but lost.

The preserved house of a jazz legend still echoes with his music.

The Vatican of the movie industry turned into an actual church.

One of the last few places in Manhattan that employed a pneumatic systemic keeps it on display.

Walk into the 19th century without leaving Brooklyn.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

A reminder to choose water over wine since 1888.

Monument to a forgotten NYC disaster that claimed the lives of 1,000.

Behind a bodega is a small museum of relics and ephemera showcasing the history of New York.

A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.