In 1119 he edited and updated the Geographica, a geographic encyclopedia first created in the eighth century by the Anonymous of Ravenna.
It followed in the tradition of earlier geographies, such as Strabo's Geographica, Pomponius Mela's De situ orbis, Claudius Ptolemy's Geography, and the Antonine Itinerary.
Guido's book included text, as well as maps of Italy and the world as it was known to the Romans.
His map of the Western Roman Empire contains the inscription Carantano, which is probably the first cartographical mention of the Slovene territory.
You can help Wikipedia by expanding it.This article about an Italian biologist is a stub.