In the medieval chronicles it is remembered as an impregnable fortress situated on a high hill (864 metres above sea level, it is the highest elevation of the Apennine buttress, of Cenozoic origin, which extends between the plateau of Gubbio and the Tiber Valley), on the border with the municipality of Perugia, and was always faithful to Gubbio.
The illustrious name of the place is: Castrum Castilionis Ildebrandi. Later transformed into "Aldobrando", whose root is in the Lombard name "Ildebrando":
hild means "battle" and brand meant at first "tizzone", then also "sword".
Then "Ildebrando" would mean "sword in battle": a bold warlike and aristocratic name.
