Emperor Constantine the Great travels to Rome to celebrate the 20th anniversary of his accession to power .
While en route at Pola Emperor orders Emperor 's older son , Crispus Caesar , to be executed , possibly on charges of adultery .
Emperor Constantine the Great travels to Rome to celebrate the 20th anniversary of his accession to power , but while en route at Pola he orders his older son , Crispus Caesar , to be executed , possibly on charges of adultery .