Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

New York City's smallest piece of private property.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

Watch the ships come in on Michigan's 210 ft. high observation deck in Sault Ste. Marie.

The only surviving prototype for Buckminster Fuller's house of the future.

Where the Model T was made and the assembly line was invented.

Astounding collection of coin-operated games and automata.

This monument honors the band's impromptu performance at Cadillac highschool's homecoming decades ago.

A horse-drawn 1858 steam pumper fire engine encased in glass on the front lawn of a Michigan insurance company.

Perched atop a brick smokestack, this enormous lug nut symbolizes the local minor league baseball team.

This mechanical wonder towers above a river in Michigan's capital city.

Glass and concrete building designed by Albert Kahn.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

The fifth-longest suspension bridge the world, connecting one Michigan peninsula to another.

Lovingly nick-named the "Brick Dick" this municipal tower was winner of the World's Most Phallic Building Contest.

This railway-turned-greenway provides a pedestrian link in downtown Detroit and celebrates urban artwork.

World's largest Christmas store.

A sealed test tube said to hold Thomas Edison's dying breath was given to the inventor's friend and mentee, Henry Ford.

A painted-over wall in Detroit originally built to segregate a black community from an adjacent white development.

Ancient petroglyphs discovered only after a massive fire swept across Michigan in the 1880s.

The writing studio of an American adventure author, built in the style of a medieval castle.

Island where motor vehicles are banned -- home to the only carless highway in the United States.

A Beaux-Arts triumph rises from decades of decay to become the heart of a new innovation district.

The Beaux-Arts aquarium boasts a vast collection of saltwater and freshwater fish on an island in the Detroit River.