The east-west walls of the Winchester, Indiana earthwork was 1320 feet or 660 X 2. The western gateway was aligned to the Summer Solstice sunset with the eastern gateway aligned to the Winter Solstice sunrise.
A few miles away from Winchester is the Fountain City earthwork that was 780 feet per side. The unique length of this work was a mystery until compared to the length of the east - west walls of the Winchester earthwork. 1320 - 780 = 540. 540 X 2 = 1080.