The Pratoni del Vivaro are the high plateau of the Castelli Romani. They are part of the regional park and cover 150 hectares between the municipalities of Rocca di Papa, Velletri and Rocca Priora. Consisting of an ancient volcanic valley squeezed by the highest peaks of the Alban Hills, they are a popular destination for outdoor sports enthusiasts, particularly horseback riding: in fact, the area is home to the Federal Equestrian Center, which organizes courses and competitions. About 300 people live in the hamlet of Vivaro and is home to the Franco Fuligni Astronomical Observatory.