Visitors can walk over the largest concentration of Columbian mammoths to have died from one event.

Thousands of people walk over this fantastic work of art every day, but how many notice it?

A stone face watches over the river.

A six-ton, 12-foot-tall concrete prairie dog is touted as the largest in the world.

The statue honors the booming birds Rothsay, Minnesota, is famous for.

Dedicated to the history of the 1,000 nuclear missiles that once covered the Great Plains.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

Every president in history is immortalized in bronze in downtown Rapid City.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

A true roadside icon standing on the same plains that the herds once roamed.

This museum is a full-size replica of an original church constructed during the 13th-century.

Wally is the 26-foot-long fiberglass emissary for Garrison, North Dakota, one of the self-proclaimed (and hotly contested) Walleye Capitals of the World.

This beautiful ancient site is dotted with perforated sandstone pillars considered sacred by some Native American groups.

The first declared National Monument in the United States.

A jaw-dropping brutalist space church seems to have crash-landed in the middle of America.

This parking garage was the site of what was - at the time - the largest cash robbery in history.

Narrowest house in Boston.

This landmark cemetery in Boston was created more than 300 years ago.

Historic Hull Street was actually the first street with a proper name in the Boston area.

The site of Paul Revere's historic two lantern warning.

A centuries-old church stands as a testament to Boston's "father of architecture."

This area was once known for being a lawless haven for rough-and-tumble sailors, earning the maritime-themed nickname "the black sea."

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

The site of one of the strangest disasters in history—a wave of deadly molasses traveling at 35 mph.