The Round Valley Ensphere is a wooden-dome stadium in Eagar, Arizona, USA. It is owned by Round Valley High School and the Round Valley Unified School District. It is the only domed high school football stadium in the United States. Opened in 1991–92 at a cost of US$11 million, the venue seats 5,500 people for football and 9,000 for basketball and volleyball. The dome encloses a floor area of 189,000 square feet (17,600 m2).