Nearly 3,000 tons of caliche went into the four-story structure. The Hohokam lacked good building materials in the desert so they went underground, using caliche that they found a few feet down. Beams made of juniper, pine and fir were brought in from mountains more than 50 miles away. A ball court and several other ruins are in the same area, but Casa Grande is the largest and most intriguing. It contains an unusual building, the Casa Grande.
Nobody really knows, but theories are plentiful.
Some say it was constructed to monitor canals that they had dug to irrigate crops. Others claim that holes visible in the walls provided the Hohokam with a timetable that told them when to plant crops. Walls face the cardinal points of a compass, and one hole in the west wall aligns with the setting sun during the summer solstice. The people who once lived in the Casa Grande raised crops using a system of canals that allowed them to irrigate corn, beans, squash, cotton and tobacco. Native desert plants also were harvested - ironwood seeds, cactus fruit, agave and grasses.