A secret, ethereal waterfall beneath the picturesque gardens.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

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

This overlooked courtyard and museum celebrate Benjamin Franklin's life and achievements.

Trace the history of the nation’s early days at the site of America’s oldest stock exchange.

The first dish to bounce radio signals off the Moon, it was the forerunner to the U.S. Space Program.

This tiny structure was built by the creator of the Brooklyn Bridge.

The way these carnivorous dinosaurs are posed is an homage to a classic work of paleoart.

A New Jersey state park that was once Napoleon's brother's sprawling estate.

Nassau Hall has served as army barracks, a museum, and played a key role in the American Revolution.

A world-class collection of mechanical musical instruments and automata.

This giant disembodied horse head seems to balance impossibly on its nose.

This strange, big-tailed beast became a Pennsylvania town's unofficial mascot.

This stone tower marks a lookout point over the historic Washington Crossing, and maybe some buried treasure.

A giant light 13 feet high shines near Thomas Edison's old Menlo Park lab.

One of the last-standing and most prominent structures from a long-lost colonial port community.

A historic town sits upon the site of a long-lost 18th-century trading community.

These unassuming lighthouses have seen the first reading of the Pledge of Allegiance, the first wireless transmission, and more than one mystery.

A bronze monument to the infamous radio broadcast in the real New Jersey town where the fictional Martians crash-landed.

Family-run for more than a century, this pizzeria makes a unique mustard pie.

This collection of odd proofs of concept is like taking a walk through the imagination of a Victorian engineer.

This Great Depression-era creation was once known as the strangest house in the world.

Lady Liberty's first beacon of enlightenment is now displayed in a museum near the statue.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.