Casa Grande Ruins National Monument is an important archaeological site in south-central Arizona that preserves the remains of a large ancient structure built by the Hohokam people around 1350 CE. The centerpiece of the monument is the “Great House,” a four-story building made of caliche (a natural concrete of mud, sand, and calcium carbonate). It is one of the largest prehistoric structures in the American Southwest.

The Hohokam were skilled farmers who built an extensive canal system to bring water from nearby rivers to their crops, allowing them to thrive in the harsh desert environment. While the exact purpose of the Great House is still debated, many archaeologists believe it may have been used for ceremonial, administrative, or astronomical purposes, rather than as a place of residence.

Casa Grande Ruins was the first archaeological site in the United States to receive federal protection, when President Benjamin Harrison designated it a reservation in 1892. It later became a national monument in 1918. To protect the fragile ruins from weather damage, a large protective roof was built over the Great House in 1932. 

Today, the monument includes a visitor center, museum exhibits, and ranger-led programs. Casa Grande Ruins offers valuable insight into the engineering skills, culture, and daily life of the Hohokam people and helps preserve their legacy for future generations.

To learn more about the monument and to plan your visit, see the parks' website. The Sonoran Desert Inventory and Monitoring network monitors a host of natural resources at the park including climate and water, vegetation and soils, and birds.