Sinnissippi Mounds in Sterling, Illinois, is a group of Havana Hopewell burial mounds on a bluff above the Rock River, preserving a tangible connection to a Hopewell culture that flourished in the area about 2,000 years ago within a broad Mississippi trade network. European settlers recognized the mounds early, and local investigators studied them in the nineteenth century, but looting and early digging removed much of their archaeological value. Even so, the site remained significant within what is now Sinnissippi Park, and the mound area received formal recognition as the Sinnissippi Site and was added to the National Register of Historic Places on May 14, 1979, as an address-restricted property.