This alley in downtown Chicago held the bodies of over 600 people after the fateful Iroquois Theatre fire.

Home to items never before seen by the public.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

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

After this former brothel closed, its interior remained almost frozen in time.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

The remote resting place of a notorious Wild West outlaw whose death is shrouded in mystery.

A popular place to pick up prehistoric coral fossils from the time when Michigan was an ocean.

This sprawling bookstore spans four floors and has more than a million books in stock.

This national park on the shore of Lake Michigan features remarkable dunes that lie at the heart of a Chippewa legend.

Largest magic museum in the United States with more than half a million pieces of memorabilia.

Astounding collection of coin-operated games and automata.

These 18th-century paintings of Warsaw were used to reconstruct the city after World War II.

Holding the most bodies of any cemetery in the United States.

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

Space program, pneumatics and more, bits and pieces, for movie sets or the common man.

The world's oldest continuously operating airport was founded by the Wright Brothers.

A wondrous old library overlooking the nation's capital.

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.

The trials and tribulations of marking Poe's grave.

A restored, one-room African-American schoolhouse in the diva's hometown now preserves the legacy of its most famous student.