| Sundown Mounds | |
| Map Type: | USA Louisiana |
| Coordinates: | 31.9347°N -91.4193°W |
| Location: | Mayflower, Louisiana, Tensas Parish, Louisiana,  United States |
| Region: | Tensas Parish, Louisiana |
| Built: | 700 CE |
| Abandoned: | 1200 CE |
| Cultures: | Coles Creek culture |
| Notes: | Responsible body: private |
| Precolumbian: | yes |
Sundown Mounds is a multimound archaeological site in Tensas Parish, Louisiana from the Early Coles Creek culture.[1] It is the type site for the Sundown Phase (600-800 CE) of the Tensas Basin and Natchez Bluff Coles Creek chronology.
The site is located on the western bank of Little Choctaw Bayou and has three platform mounds that form a triangle surrounding a plaza, a typical Coles Creek arrangement.[2] Mound A, the largest mound, is an 11feet in height and its base measures 190feet by 180feet and a summit measuring 60feet by 60feet. Mound B, the second largest, is located 400feet to the northwest of Mound A. It is 8feet in height with base measurements of 130feet by 100feet and its summit 65feet by 33feet. Mound C is 7feet with base measurements of 100feet by 80feet with a dome-shaped summit.[1] Mounds A and B had ramps from their summits down to the plaza. The mounds were constructed sometime between 750 and 800 CE,[2] but the site was occupied during most of the Coles Creek period from 700 to 1200.[1]