Narrowest house in Boston.

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

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

A former waterfront market is now in the center of town due to some interesting Boston engineering.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

The oldest inn in Kilkenny was established by the first convicted witch in Ireland.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

The ancient tomb acts as a calendar that keeps perfect time.

The modern birthplace of Irish freedom.

A museum marks and documents the site of the Titanic's launch.

One of the most popular megalithic sites in Ireland stands as a humbler version of Stonehenge.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

One of Ireland's most infamous prisons for rebels including men, women and children.

An ancient neolithic tomb that only sees the sun twice a year.

A rocky Irish outcropping with a history of wealth, conflict, and ruin.

Try not to get slimed in Tribeca.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

The oldest continuously inhabited street in America.

"A hideous albatross in the Hudson River Valley."

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.