 Constantine had known death would soon come . Within the Church of the Holy Apostles , Constantine had secretly prepared a final resting @-@ place for himself . It came sooner than he had expected . Soon after the Feast of Easter 337 , Constantine fell seriously ill . He left Constantinople for the hot baths near his mother 's city of <unk> ( <unk> ) , on the southern shores of the Gulf of Nicomedia ( present @-@ day Gulf of İzmit ) . There , in a church his mother built in honor of Lucian the Apostle , he prayed , and there he realized that he was dying . Seeking purification , he became a catechumen , and attempted a return to Constantinople , making it only as far as a suburb of Nicomedia . He summoned the bishops , and told them of his hope to be baptized in the River Jordan , where Christ was written to have been baptized . He requested the baptism right away , promising to live a more Christian life should he live through his illness . The bishops , Eusebius records , " performed the sacred ceremonies according to custom " . He chose the <unk> bishop Eusebius of Nicomedia , bishop of the city where he lay dying , as his <unk> . In postponing his baptism , he followed one custom at the time which postponed baptism until after infancy . It has been thought that Constantine put off baptism as long as he did so as to be absolved from as much of his sin as possible . Constantine died soon after at a suburban villa called <unk> , on the last day of the fifty @-@ day festival of Pentecost directly following Pascha ( or Easter ) , on 22 May 337 . 
