▁town ▁date ▁back ▁to ▁the ▁ 2 nd ▁and ▁ 3 rd ▁centuries ▁AD , ▁during ▁the ▁ancient ▁Roman ▁domin ion ▁of ▁the ▁area ▁( at ▁which ▁time ▁the ▁land ▁was ▁part ▁of ▁C is al pine ▁Ga ul , ▁due ▁to ▁being ▁inhab ited ▁by ▁C elt ic ▁pe op les , ▁such ▁as ▁the ▁In sub res ). ▁Non eth eless , ▁due ▁to ▁a ▁lack ▁of ▁arch ae ological ▁and ▁historical ▁evidence , ▁it ▁is ▁possible ▁that ▁there ▁were ▁settlement s ▁on ▁the ▁territory ▁from ▁before ▁this ▁period . ▁By ▁the ▁ 5 th - 6 th ▁century , ▁the ▁village ▁was ▁fully ▁Christian ized . ▁ ▁The ▁first ▁document ▁which ▁mentions ▁the ▁town ▁dates ▁from ▁ 8 6 5 ▁AD , ▁as ▁" C ator aci um ". ▁Another ▁appears ▁in ▁ 9 7 7 ▁AD , ▁in ▁which ▁Holy ▁Roman ▁Emperor ▁Otto ▁II ▁gave ▁the ▁Bishop ▁of ▁P avia ▁fe ud al ▁so vere ig nt y ▁over ▁a ▁territory ▁which ▁included ▁Cas or ate . ▁Due ▁to ▁being ▁under ▁such ▁a ▁rule , ▁the ▁town ▁was ▁shield ed ▁from ▁a ▁lot ▁of ▁political ▁affairs , ▁even ▁though ▁its ▁territory ▁saw ▁the ▁ 1 2 3 9 ▁battle ▁between ▁the ▁Lomb ard ▁League ▁and ▁Frederick ▁II ▁of ▁H ohen st auf en , ▁which ▁saw ▁the ▁latter ' s ▁defeat . ▁ ▁Cas or ate ▁Pr imo ▁was ▁referred ▁to ▁as ▁an ▁opp id um ▁in ▁the ▁ 1 5 th ▁century , ▁which ▁would ▁suggest ▁that ▁it