Ride the subways of yesteryear.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

Elevated freight railway turned wildly successful urban park.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

A sharp bend in a dramatic river canyon cut through red rocks.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

This massive library holds what was once the largest book collection in the world.

France's most famous cemetery, with some of its most curious tombs.

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

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.