A tiny monument to the classic American candy.

In 1958, an MIT fraternity pledge laid down on this bridge and instituted a new, unique unit of measurement.

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

Sacks of potatoes, made of cast stone, mark where the iconic potato sheds once stood along the river.

This Dutch-styled residential building was originally a cocoa company's World's Fair showpiece.

The 1920s child prodigy author was last seen here at her Brookline home before vanishing at age 25.

The oldest playground in America.

An easy-to-miss garden in Boston's North End honors the mother of JFK and others who lost children in WWII.

Ice cream stand, snack bar, and time capsule of milk conveyance.

What may be Boston's finest Art Deco building, located in the city's Financial District.

These whimsical works of art tell the story of the city's past and present.

A tiny plaque marks the location of the water source that facilitated the birth of modern-day Boston.

Shelves covered in dozens of coffee bean varieties fill this North End institution.

The infamous Boston Mob ran rackets from an office here in the 1970s.

Tragedy on Little Brewster Island memorialized.

The tomb of Increase Mather and his son Cotton, influential colonial ministers obsessed with the occult.

This memorial honors those who served on Gallops Island Radio Training Station during the second World War.

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

The word "Watergate" will forever be associated with the infamous scandal in 1972, but this fountain is famous in its own right.

This small glass cube is a peaceful out-of-the-way sanctuary at the busy airport.

Named for a Greek oracle that interpreted the words of Zeus, this beautifully-restored manor home was once home to the architect of the Marshall Plan.

Try not to get slimed in Tribeca.

Even for Egyptian royalty, the afterlife was bring-your-own-beef.

Once thought to be the fabled Holy Grail, it is now known to be an oil lamp.