It rises on the southern slopes of Monte Amiata (1,738 m) on the Plain of Rena near the town of Abbadia San Salvatore.

On 28 January 1944, during World War II, the Orvieto North railway bridge that crosses the Paglia at Allerona was the site of the inadvertent bombing by the American 320th Bombardment Group of a train filled with Allied prisoners.

One of the men on the train, Richard Morris of the U.S. Army, had been captured at Venafro, imprisoned at Frosinone, sent to P.G.

Many, including Morris, escaped through holes in the boxcars caused by the bombing, and jumped into the river below.

[3] Anglo-American historian Iris Origo wrote in her diary, War in Val d'Orcia, that "some of the carriages plunged into the river: there were over four hundred dead and wounded.