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

A spectacular remnant of an Adler and Sullivan masterpiece that was destroyed in 1972.

The unusual patterns in this rock formation result from two distinct modes of weathering.

A natural formation that resembles a camel resting in the New Mexico desert.

Kentucky, Tennessee, and Virginia meet at this point in the Cumberland Gap.

The last masonry skyscraper ever built reveals a transitional moment in architectural history.

The world's third-largest crystal sphere has sat in the Penn Museum since 1927 with the exception of one outlandish theft.

These medicine cabinet staples are part of the museum's collection of everyday objects.

Huge masonic hall in Philadelphia with lavishly themed rooms.

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

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

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

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.

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

Mural made of 100,000 pieces of hand blown glass, and one of the largest glass murals in the US.

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

A layered tribute to the work of mosaicist Isaiah Zagar.

This tribute to the 16th-century composer is now an unusual shrine to Michael Jackson.

An effigy of Vancouver's Gastown neighorhood's namesake.

Where the author wrote her beloved "Little House" books.

This opulent Pueblo Deco movie palace melds Art Deco and Native American motifs.

The first American axe throwing club.

This poignant sculpture of a gnarled weapon is a symbol of non-violence.