A grand New York post office that is home to mailman Santas, scraps of postal history, and a pneumatic mail system.

Sip a cappuccino in the historic cafe that introduced them to the United States.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

If it hadn't been caught in time, a flaw in the design of this Manhattan skyscraper could have led to its collapse.

These powerful, if squat, Canadian waterfalls flow in different directions depending on the time of day.

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

This funeral home had the honor, if that is the correct word, of hosting the funeral of the famous Sacco and Vanzetti.

What was once a true peninsula has now been filled in, causing the water to recede and leaving many streetside "waterfronts" and landlocked "islands."

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

This steep slide at a kids’ playground went viral after an police officer tumbled down it.

Dedicated to one of the darkest moments in Irish history.

This statue intended for children to enjoy became a minor political spat.

The site where Charles Dickens gave his first public reading of "A Christmas Carol" in the US.

Dedicated to a colonial woman who was hanged for being a Quaker.

This bronze sculpture was inspired by a photograph of Martin Luther King Jr. and his wife embracing after he won the Nobel Peace Prize.

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

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

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

Second largest wastewater treatment plant in the country.

You can spend the night as an honorary lighthouse keeper in this quaint, historic beacon.

The oldest still-operating tavern in the United States was once owned by a pirate.

Oldest synagogue in the United States.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

A 60-room castle constructed by a horse-racing heir.