This elaborate towering structure was once famed for its revolutionary height.

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

A layered tribute to the work of mosaicist Isaiah Zagar.

In the early 1800s, surgery was also a show.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

A museum dedicated to the strange and extravagant costumes and memorabilia of the mummers, a tradition older than Philadelphia itself.

Current docking place of the SS United States, the fastest transatlantic ocean liner.

The rusting remains are visible sticking out of the waters of the Delaware Bay.

The United States Capitol's former columns still stand.

Largest Roman Catholic church in North America.

The privately owned cemetery that holds room for Washington's finest when they step down from life.

The "lovely red Vega" of the legendary record-settling pilot.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

Giant acorn-shaped 19th century gazebo from which suburban Washingtonians gazed upon the original "silver" spring.

An astounding collection of medical specimens, including bits of President Lincoln.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.