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

The oldest surviving presidential residence in the United States.

Golden and naked, the figure that was once the highest point in New York is all that remains of the second Madison Square Garden.

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

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

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.

A layered tribute to the work of mosaicist Isaiah Zagar.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

Memorial built in 1922 in remembrance of WWI casualties.

The third-tallest lighthouse in the United States stands as a reminder of Atlantic City's early days.

Amazingly, this old machine within the Resorts Casino still functions.

A burial ground for workers at one of Hawai'i's largest sugarcane producers that laid buried for decades.

A glass display case holds the document that ended the Second World War—which one person signed on the wrong line.

These fossilized remains of an ancient saber-toothed cat inspired the mascot of Nashville's NHL team.

In 1912, a broken section of the reservoir wall released millions of gallons of water and destroyed many homes downhill.

Located inside a former record pressing plant, this recording studio pays homage to the techniques and gear of a bygone age.

This replica of the Greek structure is in the heart of Nashville.

The grave of America's 11th president is not in some grand monument but instead it's hidden away on the grounds of the Tennessee Capital.

When Motown musicians came to Nashville in the 1960s they stayed at this historic record-pressing company because hotels wouldn't host them.

The "lovely red Vega" of the legendary record-settling pilot.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

The privately owned cemetery that holds room for Washington's finest when they step down from life.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.