Sniff the Titan Arum's rotting flesh.

The "Seinfeld" diner.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

Elevated freight railway turned wildly successful urban park.

A crumbling hospital from the 1850s on Roosevelt Island.

This beloved marketplace mascot poops money and grants good luck.

The sounds of the world's largest fully functioning pipe organ dazzle shoppers at a Philadelphia Macy's.

The first American department store, and home to the largest operating musical instrument in the world.

This elaborate towering structure was once famed for its revolutionary height.

This little-known collection holds everything from "Dracula" notes, to the manuscript of "Ulysses," to the forged works of Shakespeare.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

World's first "penitentiary," meant to be humane, drove men insane.

Dr Barnes' $25 billion private collection of art and arboretum.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

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

The oldest surviving botanic garden in the United States.

One artist's love letter to his city and its citizens plays out across dozens of bright murals painted on the sides of decrepit buildings.

The corporeal remains of Napoleon III's dentist rest under this 15-story obelisk.

The oldest of only three existing statues of the great novelist stands in a city he did not care for.

Hidden behind West Philadelphia rowhomes is a haven for migratory and local bird species both ordinary and rare.

A tiny, unmarked beer and whiskey bar above an Ethiopian restaurant in West Philly fails to conceal live bluegrass.