The Val di Chiana is about 100 kilometres (62 mi) long, and covers about 2,300 square kilometres (890 sq mi). It runs north to south between the plain of Arezzo and the plain of Orvieto and includes the watershed of the Canale Maestro della Chiana, its main watercourse, and the northern part of the watershed of the Chiani River. To the northeast it is bounded by the Tuscan pre-Apennines crowned by the Alta Sant'Egidio at 1,057 metres (3,468 ft), monte Lignano at 837 metres (2,746 ft), and monte Corneta at 744 metres (2,441 ft). To the southeast, it reaches Lake Trasimeno and the valley of the Nestore River. To the west, it extends to the Val d'Orcia, where it reaches its highest elevation at 1,148 metres (3,766 ft) on (Monte Cetona). The landscape is mostly hilly, with a plain around the Canale Mastro. Its mean elevation is around 405 metres (1,329 ft).
