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.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

A whimsical, but often overlooked clock in Park Avenue.

Visit the monolithic tomb of America's most famous general.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

A curious fountain that has no water and includes Satan, a crab, and 9 giraffes.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

The oldest operating apothecary in the US has treated everyone from Thomas Edison to Mark Twain.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

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

France's most famous cemetery, with some of its most curious tombs.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

This Italian-style temple replica has been threatening to fall off the Irish coast for hundreds of years.

Northern Ireland's Brobdingnagian stepping stones.

The atmospheric road was never meant to be so creepy.

This short bridge is the only thing connecting a tiny Irish island to the mainland.

This Victorian-era public house has set the standard for pub-style elegance for over a hundred years.

A museum marks and documents the site of the Titanic's launch.

The lake that fills and empties itself at random.

A drab two-story office space in Delaware is a hidden tax haven for Hillary Clinton, Donald Trump, and over half the Fortune 500 companies.

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

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

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