This beautiful architectural gem was the first waste treatment facility in Boston.

Last church of this militaristic WWII style.

The remains of a hospital ravaged by fire, once a progressive place of innovations for disabled children.

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

The ruins of one of the first railroads in the U.S. lie hidden within a neighborhood cul-de-sac.

Located in a beautifully restored ice house, this museum is the result of decades of hard work and devotion to the craft of plumbing.

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

This historic cemetery is filled with markers that look more like candy than was likely intended.

The former site of an all-but-forgotten colonial landmark is now remembered by an often overlooked bas relief.

This Gothic castle was inspired by Erik the Red's Viking residence at Brattahlid in Greenland.

Dedicated to one of the darkest moments in Irish history.

A plaque memorializes the Boston location of one of the largest nightclub fires in history.

A unique columnar residence built in the 19th century.

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

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

This area was once known for being a lawless haven for rough-and-tumble sailors, earning the maritime-themed nickname "the black sea."

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

Tragedy on Little Brewster Island memorialized.

Civil War Fort on an island in the Boston Harbor.

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

The birth home of one of cinema's legendary actresses.

The oldest working bell set in North America, the bells at Old North Church sat silent for their first four years in Massachusetts.

This hidden labyrinth offers walkers some brief peace of mind.

The strikingly modern structure stands out among the brick buildings speckling the Harvard Business School's campus.