Round Valley Ensphere, domed high school football stadium in Eagar, Arizona, United States

The Round Valley Ensphere is a wooden dome structure in Eagar that encloses a vast indoor space suitable for multiple activities and gatherings. The roof spans across a large diameter with considerable height, creating an open interior free of support columns.

In 1987 voters passed a $12 million bond for the dome and repairs after it emerged that Tucson Electric Power, which generates 90% of local property values, would pay $11 million of it; the utility sued to block construction and lost in trial and appellate courts. Building began in summer 1990 and paused three months for reinspection after two workers were killed by falling wooden beams. The first football game was played on October 11, 1991, against Payson High School, and in September 2024 the facility was renamed for former head coach Tot Workman.

The dome is named after Tot Workman, the former head coach honoured when the school renamed the facility in September 2024. It also hosts non-school events such as a car show, and in 2002 it sheltered 9,800 evacuees of the Rodeo-Chediski fire, tripling Eagar's population overnight.

The dome seats 5,500 for football and 9,000 for basketball and volleyball, and its 189,000-square-foot floor holds football, basketball, track and field, and soccer. It sits in Eagar, about 0.87 km west of the town center, at roughly 2,195 m elevation. The building was closed for nearly a year after 2015 rain damage, so check current access before travelling.

The Ensphere was the first fully day-lighted dome of its kind, letting sunlight and heat enter through its wooden shell. In 2002 the Rodeo-Chediski fire turned it into a shelter for 9,800 evacuees, tripling Eagar's population overnight and nearly overloading the town's sewage system.