Millions of numbers carved in glass represent the tattoos forced upon victims.

Impossibly life-like natural history models created out of glass by a father and son.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

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

American revolutionaries and British soldiers alike are buried here in the fourth-ever cemetery in Boston.

Mrs. Mallard and her brood are a beloved fixture in Boston Public Garden.

Two thousand artifacts from around the world collected by one woman who loved to travel.

This impressive Boston holy house is the American mecca for Christian scientists.

In 1958, an MIT fraternity pledge laid down on this bridge and instituted a new, unique unit of measurement.

This bridge was the birthplace of a unit of measurement based on a fraternity joke.

The oldest house in Galena, Illinois, now is a reminder of when this city was the world's lead mining capital.

A wonderland of caves in eastern Iowa.

The oldest university museum west of the Mississippi retains its 19th century feel.

A mysteriously dark cemetery monument fuels stories and legends galore.

Remnants of a quarry company town still stand on the banks of the Wapsipinicon River.

One of just a few cities in the world to base their center of government on an island. Others: Paris and Osaka.

A hidden barn-sized rendition of Grant Wood's most famous, and most parodied, painting.

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

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

The location where the iconic movie character declared it was time to go home.