One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

This unique museum cafeteria showcases the history and regional diversity of African American cuisine.

Look closely and you’ll notice that the color changes a third of the way up the tower.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

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

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.

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

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

Mrs. Mallard and her brood are a beloved fixture in Boston Public Garden.

This bridge was the birthplace of a unit of measurement based on a fraternity joke.

In 1958, an MIT fraternity pledge laid down on this bridge and instituted a new, unique unit of measurement.

A giant bisected onion dome remembers the Iraqis who died in the Iran-Iraq War.

This massive Maya archaeological site is home to the tallest man-made structure in Belize.

Sparkling, calcite-covered skeletons of children who may have been sacrificed to appease an angry god.

Diego Rivera hid various people and symbols in his first large-scale mural project.

Frida Kahlo's childhood home, now a museum of her life and works.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This steep cable railway has been hoisting passengers in the heart of Québec City for over a century.