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

From economic backbone of a community to deadly diving hole, these former stone quarries are now a park for rock climbers and graffiti artists.

The world's largest piece of copyrighted artwork.

The site of the tragic isolation of Nipmuc Native Americans left to perish in King Philip's War.

Second largest wastewater treatment plant in the country.

Civil War-era Fort designed to withstand invasion and attack, with tricky traps called "murder holes."

Last church of this militaristic WWII style.

Trash escaped from a landfill to fill beaches with all kinds of treasure.

A daybeacon pyramid is about all that's left of this island that is said to have sunk due to a pirate's curse.

Hill-like structures formed by glaciers and sandy spits of land.

Solar powered Spectacle Island features all-green facilities.

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

This tiny, painted door at the base of a tree stump has been a fixture of the Harvard University campus for decades.

The self-proclaimed world's smallest museum, located next to a Massachusetts sandwich chain.

More than 5,000 artifacts donated by the people of the city, plus a room entirely devoted to the band U2.

Known as one of the most climbed mountains in the world, this barren peak is permanently bald thanks to an anti-wolf fire.

The skeletal white beams stand as a monument to religious dissent.

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

Memorial to a beloved puppeteer as well as all street performers.

One of America's most historic homes also holds a startling literary legacy.

Final resting place of the author who wrote the ghost story "The Turn of the Screw," and his brother, the Harvard doctor and paranormal investigator.

Painstakingly built dioramas sit unnoticed in a Boston office building.

America's original house of worship for Spiritualism, the religious movement based on communing with the dead.

One of the now-less-hidden floral gems of the "Emerald Necklace."