▁Duke ▁Alfonso ▁I ▁d ' E ste ▁and ▁was ▁later ▁returned ▁to ▁the ▁Pap al ▁States ▁in ▁ 1 5 9 8 . ▁ ▁South - east ▁of ▁the ▁city ▁lies ▁the ▁small ▁historic ▁fort ification ▁of ▁P ieve ▁di ▁Cent o . ▁ ▁Main ▁s ights ▁Pal azzo ▁del ▁Monte ▁di ▁Piet à ▁( 1 8 th ▁century ), ▁housing ▁the ▁C iv ic ▁Gallery . ▁It ▁has ▁paint ings ▁by ▁the ▁local ▁artist ▁Gu erc ino . ▁The ▁latter ' s ▁works ▁can ▁be ▁seen ▁also ▁in ▁the ▁Bas il ica ▁Colleg i ata ▁San ▁Bi ag io , ▁Santa ▁Maria ▁dei ▁Ser vi , ▁the ▁church ▁of ▁the ▁Ros ary , ▁also ▁designed ▁by ▁him , ▁and , ▁in ▁the ▁fra zione ▁of ▁Corpor eno , ▁the ▁ 1 4 th - century ▁church ▁of ▁San ▁Giorg io . ▁The ▁Roc ca ▁( Cast le ), ▁a ▁massive ▁square ▁building ▁with ▁square ▁to wers . ▁Bu ilt ▁in ▁ 1 3 7 8 ▁by ▁the ▁bishop ▁of ▁Bolog na , ▁it ▁was ▁en larg ed ▁by ▁Giul io ▁della ▁R over e , ▁the ▁future ▁po pe ▁Julius ▁II , ▁in ▁ 1 4 6 0 . ▁Pal azzo ▁del ▁Govern atore ▁( G overn or ' s ▁Palace , ▁ 1 5 0 2 ). ▁It ▁is ▁home ▁to ▁the ▁Gall eria ▁d ' arte ▁modern a ▁A ro ld o ▁Bon z ag ni . ▁Port a ▁P ieve ▁( 1 4 th ▁century ), ▁the ▁sole ▁surv