By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

Allowing humans and fish alike to migrate from freshwater to saltwater and back again.

A giant Troll lurks under one of Seattle's oldest bridges.

A wall of chewing gum moonlights as collective art.

A museum within a museum, devoted to history's most questionable medical devices.

"the sweltering inhabitants of Charleston and New Orleans, of Madras and Bombay and Calcutta, drink at my well . . . The pure Walden water is mingled with the sacred water of the Ganges."

This massive World War II calculator hearkens back to the days when "computer" was a job title.

"Mock all and sundry things, but leave the saints alone."

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

The site of Paul Revere's historic two lantern warning.

The site of one of the strangest disasters in history—a wave of deadly molasses traveling at 35 mph.

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.

Rising 30 feet in the air atop Quarry Hill, the Old Powder House is the oldest stone building in the state of Massachusetts.

Three prestigious academic collections come together to create a world-class natural history museum.

Impossibly life-like natural history models created out of glass by a father and son.

This nearly endless university hallway is home to a unique sunset known as "MIThenge."

This bridge was the birthplace of a unit of measurement based on a fraternity joke.

This impressive Boston holy house is the American mecca for Christian scientists.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

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 semi-scholarly approach to sex.

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

Twice a day one of these tragic bronze mariners drowns with the tide to remember all those the sea has taken.

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