A clone-tree in Washington Square Park sprung from seeds that went to the Moon and back.

Step into a pastel time capsule where candy is truly dandy.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

The oldest active church in Pennsylvania is also the second oldest Swedish Church in the United States.

Alexander Hamilton’s creation caused quite a bit of controversy.

An Irish Memorial commemorating those who perished due to potato blight.

Ant sculptures march up the side of what used to be an iconic spot in punk rock lore.

America’s smallest national park site is the former residence of exiled Polish national hero Thaddeus Kosciuszko.

One of the oldest of its kind.

South Philadelphia is home to Keith Haring's only surviving in situ collaborative public mural.

The singer, actor, and activist lived here during his final years, and now it’s a museum dedicated to his legacy.

Hidden behind West Philadelphia rowhomes is a haven for migratory and local bird species both ordinary and rare.

The corporeal remains of Napoleon III's dentist rest under this 15-story obelisk.

The oldest of only three existing statues of the great novelist stands in a city he did not care for.

This 15-foot tall obelisk commemorating the Philadelphia-Baltimore railroad connection sat neglected for over a century.

The oldest surviving botanic garden in the United States.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

America's first serial killer rests in anonymity.

North America's oldest quarantine facility was built in response to Philadelphia's 1793 yellow fever outbreak.

Surrounded by industrial sprawl, a small monument marks the site of William Penn's first landing in Pennsylvania.

The highest point in Delaware is located under a trailer so this marker across the street will have to do.

This splendid Versailles-inspired mansion has the largest French-style formal gardens in North America.

Enchanting gardens surround a derelict mansion, all hidden in plain sight behind a stone wall.

A drab two-story office space in Delaware is a hidden tax haven for Hillary Clinton, Donald Trump, and over half the Fortune 500 companies.