Casas Grandes (Spanish for Great Houses; also known as Paquimé) is a prehistoric archaeological site in the northern Mexican state of Chihuahua. Construction of the site is attributed to the Mogollon culture. Casas Grandes has been designated a UNESCO World Heritage Site under the purview of INAH and a "Pueblo Mágico" since 2015.

Casas Grandes is one of the largest and most complex Mogollon culture sites in the region. Settlement began after 1130 AD, and the larger buildings developed into multi-storied dwellings after 1350 AD. The community was abandoned approximately in 1450 AD. Casas Grandes is regarded as one of the most significant Mogollon archaeological zones in the northwestern Mexico region, linking it to other sites in Arizona and New Mexico in the United States, and demonstrating the extent of the Mogollon sphere of influence.

The Casas Grandes complex is situated in a broad, fertile valley along the Casas Grandes or San Miguel River, approximately 56 kilometres (35 mi) south of Janos and 240 kilometres (150 mi) northwest of the state capital, Chihuahua. The settlement depended on irrigation to sustain its agricultural activities.

The archaeological zone is contained within the eponymous modern municipio (municipality) of Casas Grandes. The valley and region have been inhabited by aboriginal groups for millennia.

Between 1130 and 1300 AD, the area's inhabitants started gathering in small settlements within this expansive fertile valley. The most extensive identified settlement is now recognized as Paquimé or Casas Grandes. It originated as a collection of 20 or more clusters of houses, each with a plaza and enclosing wall. These single-story adobe dwellings shared a unified water system. Evidence indicates that Paquimé possessed an intricate water management system comprising underground drain networks, reservoirs, channels for water distribution to the residences, and a sewage system.

After being burned about 1340, Casas Grandes was rebuilt with multi-story apartment buildings to replace the small buildings. Casas Grandes consisted of about 2,000 adjoining rooms built of adobe, I-shaped Mesoamerican ballcourts, stone-faced platforms, effigy mounds, and a market area. About 350 other, smaller settlement sites have been found in the Casas Grandes area, some as far as 70 kilometres (43 mi) away. Archaeologists believe that the area directly controlled by Casas Grandes was relatively small, extending out about 30 kilometres (19 mi) from the city. The population may have been about 2,500 in Casas Grandes with perhaps 10,000 people living within its area of control.

Specialized craft activities included the production of copper bells and ornaments, extensive pottery, and beads from marine molluscs. These crafts were probably distributed by an extensive trading network. Casas Grandes pottery has a white or reddish surface, with ornamentation in blue, red, brown, or black. In the past it was sometimes considered to be of better manufacture than the contemporary pottery in the area. Effigy bowls and vessels were often formed in the shape of a painted human figure. Casas Grandes pottery was traded among prehistoric peoples as far north as present-day New Mexico and Arizona and throughout northern Mexico.

The archaeologist Stephen Lekson has noted that Paquimé is aligned on roughly the same longitudinal axis as Chaco Canyon and Aztec Ruins, with an error of only a few kilometres/miles. Chaco reached its cultural peak first, then Aztec and Paquimé. The similarities among these sites may indicate that their ruling elites also had a ceremonial connection. Lekson proposed that ruling elites, once removed from their prior positions at Chaco, re-established their hegemony over the area at Aztec and later Paquime. This idea, though, remains controversial and is not as widely accepted as often reported (cf. Lekson 2009). It has been proposed, and more widely accepted, that the origins of Paquime can be found in its connection with the Mogollon culture.