Stay at this storybook estate, featuring Sir Henry Hudson Kitson's masterpiece "Gingerbread House."

The location where the famed author and abolitionist began his journey to freedom.

Lines from a walking song are etched into a rock in Natural Bridge State Park.

A railroad tunnel that, upon its completion, was considered one of the engineering marvels of the modern world.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

This unassuming North Austin neighborhood was built to test the novel idea of home air conditioning.

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

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

Dr Barnes' $25 billion private collection of art and arboretum.

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

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.

These unusual rooms on wheels are holdovers from the 1960s.

This former Cold War missile control site played an important role in the creation of GPS.

An out-of-place Air Force radar dome is all that denotes this park as a former missile launch site.

A clone of a cloned tree that was so important it allegedly had its own guards.

From this desk Al Hirschfeld drew his influential caricatures of the 20th century's Broadway stars.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Though its celestial ceiling is impressive, the true star is the vast collection of French books.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

This lavish room at NYC's French Embassy is a rare relic from the end of the Gilded Age.

The front yard of an Upper East Side town house hides the last fragment of one of New York's most famous theatres.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.