The province is mostly mountainous with the Monti della Duchessa and the Monti del Cicolano ranges in the south with Monte Nuria and Monte Giano, the Monti Reatini range with Monte Terminillo (2217 m) in the north in part of the Abruzzese Apennines, and Monti della Laga (2458 m) to the east on the border with Abruzzo. Of particular importance are the two artificial lakes in the Valle del Salto: Lago del Salto and Lago del Turano, which were both created during the Fascist period. Lago del Salto, also known as Del Salto Lake is the largest in the Lazio region and is situated at an altitude of .