The ruins of a medieval monastery named after a type of tree.

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

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

The last remnants of Fort Pitt also hold the distinction of being the oldest structure west of the Allegheny Mountains.

Sections of the iconic limestone columns have been left uncleaned as a reminder of the city's polluted past.

Despite being stolen multiple times, this civic electrician's street corner Snoopy won't be stopped.

There aren't too many operational funiculars around, but Pittsburgh has two!

One of the oldest hospitals in the Americas is now decorated in hallucinatory murals.

One of Mexico’s historic pottery-producing towns is home to a museum showcasing the craft.

Dr Barnes' $25 billion private collection of art and arboretum.

Huge abstract sculptures of the Puerto Rican Flag.

Once called the "Polish Gold Coast" it is an icon of the neighborhood that bears its same name.

First planned industrial community in the United States.

Each of these gorgeous, intricately decorated rooms is painstakingly crafted to the scale of 1 inch: 1 foot.

The site of the first couple's first kiss is commemorated by the most adorable presidential monument ever.

A Bibliophile's Dream.

WWII-era bunkers are hidden under the beaches of this picturesque park, which is still scattered with wartime watchtowers. .

The "All-Seeing Eye of God" symbol on this library is a clue to one of the many former lives of this building.

A monument marks the location of the first successful steamboat demonstration.

Statue in Salem of the woman who starred as the witch Samantha in the sitcom "Bewitched."

The only structure left with direct ties to the Salem witchcraft trials of 1692.

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

Crammed into a Baltimore row house is an oddities shop that sells everything from skulls to dead insects.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.