Tempe sits in the Salt River Valley of central Arizona, a college city built around Arizona State University. The university's main campus fills the city with students, research, and Sun Devil sports, and Mill Avenue, the main street beside campus, offers shops, restaurants, and live music. Tempe Town Lake, a reservoir on the Salt River, gives residents boating, festivals, and a waterfront path through downtown. Hayden Butte, a rocky hill known as A Mountain for the gold letter on its side, rises above the lake and rewards climbers with a view across the Valley.