an Entity references as follows:
The Damariscotta Shell Midden Historic District encompasses a significant collection of shell middens along the Damariscotta River in Lincoln County, Maine. It includes eleven middens in all, including the well-known Whaleback Shell Midden and the Glidden Midden, which is the largest shell midden in the northeastern United States. The area has the largest concentration of such midden sites under conservation protection in the eastern United States. The district was listed on the National Register of Historic Places in 1998.