Sears-Kay Ruin, Archaeological site in Carefree, United States.

Sears-Kay Ruin is a Hohokam fortification on a desert foothill in Tonto National Forest outside Carefree, Arizona. About 40 stone rooms housed roughly 100 people, and low dry-stone walls of flat grey, brown and tan rocks, laid without mortar, still step and curve across the hillside.

The Hohokam people built this settlement around 1050 and lived there for roughly 150 years. They left around 1200, and no one has yet found a clear reason for their departure.

The name Sears-Kay comes from the Sears-Kay Ranch, founded by J.M. Sears in 1887 on the land where soldiers of the 5th Cavalry Regiment came upon the fort in 1867. The site lies on Tonto National Forest land, and the trail is lined with signs describing each ruin; a sign at the base of the hill is titled "Walk in the Path of Ancient Hohokam at Sears-Kay Ruin".

The ruins are reached by a short hiking trail with a moderate elevation change, so sturdy shoes are a good idea. Desert conditions mean the heat can be intense, and carrying enough water is important, especially in summer.

One chamber on the site, known as the Mystery Room, has rounded corners instead of the square angles found in every other room. Researchers have not yet found a convincing explanation for this difference, making it one of the more puzzling details of the site.