This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

Where you can hail your favorite fictional commanders-in-chief.

This fertility idol of questionable authenticity inspired an iconic Indiana Jones artifact.

The sounds of the world's largest fully functioning pipe organ dazzle shoppers at a Philadelphia Macy's.

The first American department store, and home to the largest operating musical instrument in the world.

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

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

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

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

The body of St. John Neumann and his collection of hundreds of relics, on display in a Philly church.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

One of Philadelphia's largest murals resides hidden under this bridge.

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

One of the oldest of its kind.

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

A completely round house designed for the Atomic Age.

The final resting place of one of the United States's greatest poets.

The first partially complete dinosaur skeleton was discovered here, forever changing the world's view of the ruling reptiles.

An unusual assortment of steerable wooden sleds is on display in a library in New Jersey where they were first invented.

The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

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

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

A daily replay of the experiment that proved the rotation of the Earth.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.