This limestone cave offers an incredible view of the Río Grande de Arecibo valley.

The abandoned coal loading dock is a canvas for unsanctioned art.

An Irish Memorial commemorating those who perished due to potato blight.

Believed to be the birthplace of the United States Marine Corps.

A layered tribute to the work of mosaicist Isaiah Zagar.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

The oldest surviving botanic garden in the United States.

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

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

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

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

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

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

The world’s first penitentiary, meant to be humane, drove men insane.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

The giant birds honor two native North American species.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

This Niagara Falls tourist trap is a world bright with neon and curiosities that will inspire love, hate, or a mixture of both.

"Gnome Chomsky" was once the largest gnome in the world, but is now simply tall for his kind.

An abandoned castle owned and ignored by Masons carries a cursed history.

This Central New York ghost town was once a prosperous railroad community.

This sculpture of a fisherman spent six years at the bottom of the Schuylkill River.

The colonial city's social history is reflected in its fanciful door knockers.

A cozy bookstore and coffee shop in the heart of Cartagena's Old City.