River
Fluvius Umbro
Ambra
The map draws a single river line here, labelled Fluvius Umbro, yet it probably stands for two rivers merged into one. The name belongs to the Ambra, a stream in the province of Arezzo in Tuscany that joins the upper Arno from the left, but the mapmakers seem to have fused it with the Ombrone, which runs to the Tyrrhenian Sea. That is why one river carries the name Umbro twice. The muddle spreads further: close together, the map records five places called Umbro, the two rivers and three road stations marking bridges, one over the Ambra, one over the Ombrone near Siena and one near the coast.