Troyville Earthworks (16 CT 7) is a Woodland period Native American archaeological site with components dating from 100 BCE to 700 CE during the Baytown to the Troyville-Coles Creek periods. It once had the tallest mound in Louisiana at in height. It is located in Catahoula Parish, Louisiana in the town of Jonesville. The site is the type site for the Troyville culture of the lower Ouachita and Tensas River valleys. Before it was destroyed for bridge approach fill in 1931, the main mound at Troyville was one of the tallest in North America. Site description The site is at the confluence of the Tensas, Ouachita, and Little Rivers. It had nine platform mounds and a perimeter embankment that were built before 700 CE. A historian, John W. Monette, in 1844 described the complex as occupying close to 400 acres and noted the existence of twelve small mounds and one large one. The embankment was started during the Middle Baytown period, with periodic repair work taking place during the Late Baytown period. The largest mound, Mound 5 ( also known as the "Great Mound" ), was in height. It was the tallest precolumbian mound in Louisiana and the second tallest in North America. Its base covered an acre of ground and had three levels, the bottom two rectangular and the third on the top a truncated conical mound. Monette described the lower level of Mound 5 as being by at its base and rising to the height of . He described the conical mound at the top as . Measurements for the smaller mounds at the site were about to in height with bases measuring by . Four of the mounds were surrounded on the southern and western side of the plaza by the embankment, which measured in height, in width and across. By the time of the American Civil War, the mound had been reduced in size to in height. During the Civil War, the mound was reduced even further when some of its fill was removed to construct Confederate rifle pits. In 1871 the town of Jonesville was founded on the site and more of Mound A's fill was used to fill ditches (borrow pits created by the removal of earth to construct the mounds themselves) and level the land as the town grew. The townspeople frequently camped out on the mounds during flooding. In 1883 the site