Statue commemorating the use of ether in anesthesia.

Mrs. Mallard and her brood are a beloved fixture in Boston Public Garden.

The Boston square dedicated to the dark poet who was born nearby.

The history of the tea trade is told in bas-relief on this historic pair of Boston doors.

An enormous, inside-out glass globe built in 1935.

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

Painstakingly built dioramas sit unnoticed in a Boston office building.

A careful eye can find hundreds of dinosaur tracks running along the Connecticut River.

This tea house was a hand-built gift from Boulder's sister city in Tajikstan.

Herman Melville wrote 'Moby Dick' in this landmark 18th-century house surrounded by farmland.

A suburban museum tells the story of a historic transportation network and even provides rides in antique trolley cars.

Walk a trail through a historic Quaker town that outlawed slavery in 1777 and was a major waypoint on the Underground Railroad.

A lawn full of retired spacecraft on display at one of NASA's first research labs.

This cemetery served as the only official burial grounds in Cambridge for nearly 200 years.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

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

A medieval tower with a suspended iron cage used as an open-air jail for criminals who were exposed as a warning.

A star fort along the C&O Canal in western Maryland that protected America in three wars.

A monument marks the location of the first successful steamboat demonstration.

A relic of FDR's brief foray into utopian urban planning.

The rooster who crossed the road lives on forever in Takoma Park, Maryland.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

An ear-piercing buzzer calls lawmakers to a vote with a series of long and short rings to form coded messages.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.