Here we have 3 of the most well known sites in North America.  Chichen Itza and Teotihuacan are amongst the largest pyramids and archeological sites in the Americas.   Cohokia mound is one of the larger sites in North America.  While from 3 different cultures and time periods, they create a 30-60-90 triangle which is aligned almost directly north on one side.    The longest side is over 1400 miles long.