National Historic Landmark - The Pillsbury A-Mill

The Pillsbury A Mill, built of Platteville limestone, was the world’s largest flour mill when it was completed in 1881. The design by LeRoy S. Buffington is considered a classic of industrial architecture, and the interior of the mill boasted ...

National Historic Landmark - Portland Observatory

has been designated a

National Historic Landmark

This site possesses national significance

in commemorating the history of the

United States of America.

The Observatory is the nation's only remaining maritime signal tower. It served as a communication station for Portland's ...

Delaware Historic Civil Engineering Landmark

Chesapeake & Delaware Canal

Designated 1982, Delaware Section, ASCE

Marker can be reached from Clinton Street.

Courtesy hmdb.org