Toltec Mounds - A Giant Calendar

Going back and looking at Toltec Mounds. The site pattern is the same cookie-cutter mound set up as all along the Mississippi. The sites are always by a water supply, some sort of barrier, and are set up as calendars.

https://en.wikipedia.org/wiki/Toltec_Mounds_Archeological_State_Park

http://www.arkansasstateparks.com/toltecmounds/