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

This headstone-like marker inscribed with three words has been an utter mystery for over a century.

The nation's second-ever First Lady urged the founding fathers to "remember the ladies."

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

This giant Boston statue of Mary is standing on a globe to show her power over the universe.

On a former island, this old fortification once used to protect the Boston Area and started Edgar Allan Poe in his military career.

Massachusetts memorial to murder victim Elizabeth Short near the spot where she was born.

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

Run by a eugenics advocate, this aging institution conducted secret radiation experiments sponsored by Quaker Oats.

A little Lego easter egg is hidden underwater in the Boston Tea Party tableau at Miniland.

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

This ambitious father and son team reigned supreme over the North End, and witches, for many years.

The final resting place of a suffragist author.

Millions of numbers carved in glass represent the tattoos forced upon victims.

This "life-size" depiction of Mickey Mouse as a half-lobster is both whimsical and a bit creepy, standing guard over the Boston waterfront.

The remnants of a Gilded Age elegance preserved in the middle of a stark modern tower.

The massive machine creates cracking displays of indoor lightning.

A more than 260-year-old crypt built on Boston's oldest English burial ground.

A morbid secret lies hidden within the beautiful walls of the Boston Athenaeum.

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

19th-century operating theatre in which the use of ether was first demonstrated - plus, a skeleton and a mummy!

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

This headstone marks the grave of an 11-year-old boy killed during clashes in the streets over the boycotting of British goods.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.