Along the middle course, the hill of Todi. And: Forello ravine, Orvietane fortresses in Prodo and Titignano. Again, Corbara and Alviano Lakes, the latter an essential shelter for migratory and resident birds. In the surroundings, large and untouched oak and holm oak woodlands and, near the river, the archaeological remains of the Umbrian, Etruscan, and Roman civilizations; castles, or their ruins, which belonged to past commanders.