Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

This magnificent Japanese garden provides a moment of Zen in rural Vermont.

Its interior is adorned with some of the best examples of early Christian mosaics.

A sculpture serving as an homage to Pope John Paul II.

A Nesting Doll of Churches.

Naturally formed white marble arch housed in an abandoned marble quarry from the 1800s.

Inspiring Herman Melville and Henry David Thoreau, Mount Greylock in western Massachusetts is the highest point in the state at 3,491 feet above sea level.

Resonating tubes make music from highway overpass.

More than 200 unconventional musical instruments that anyone can play.

This sprawling 18th-century cemetery features unique and beautiful gravestones, including one shaped like a tree.

This abandoned neighborhood is now a park filled with beautiful trees, wildflowers, and hints of its past.

The first piece of public art dedicated to LGBT rights.

Hiroshima survivor on Riverside Drive.

The site of the deadly Triangle Shirtwaist Factory Fire.

A curious fountain that has no water and includes Satan, a crab, and 9 giraffes.

This wall on a street corner in Lower Manhattan has been a blank canvas for a rotation of renowned artists since the 1980s.

This enormous Hindu temple in Queens serves incredible dosas in its basement canteen.

An artist's cute bronze subway sculptures belie his violent artistic past.

Curious crustaceans support an obelisk from ancient Egypt that now stands in modern-day Central Park.

Lie in a hammock where George Washington stood.

The only home that Alexander Hamilton ever owned has a history almost as troubled as his own.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.