One of the first intercontinental ballistic missile sites in the United States.

A series of life-sized statues of each governor of the state of South Dakota.

A tunnel with windows, so you don't miss out on the impressive views.

The fifth-longest natural arch in the world, and the longest outside China.

At this Minnesota state park you can easily wade across the source of the mighty Mississippi.

Liechtenstein's royal family calls this medieval alpine castle home.

This ancient theater was once the home of fierce gladiatorial battles.

Breathtaking and huge 430 year old maps of Italy.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

A beautiful but toxic fountain of mercury.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

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

A Beaux-Arts triumph rises from decades of decay to become the heart of a new innovation district.

Narrowest house in Boston.

This landmark cemetery in Boston was created more than 300 years ago.

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

The first home and studio that belonged to the famous architect.

The oldest hotel in West Virginia is reportedly frequented by ghosts.

Catch rising stars of Appalachia’s music scene before they make it big at this restaurant and community hub.

A memorial to the most decisive Native American victory of the Plains Indian War.

The headquarters of the famous Yale society.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

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