 Constantine began a major expansion of Trier . He strengthened the circuit wall around the city with military towers and fortified gates , and began building a palace complex in the northeastern part of the city . To the south of his palace , he ordered the construction of a large formal audience hall , and a massive imperial bathhouse . Constantine sponsored many building projects across Gaul during his tenure as emperor of the West , especially in Augustodunum ( Autun ) and Arelate ( Arles ) . According to Lactantius , Constantine followed his father in following a tolerant policy towards Christianity . Although not yet a Christian , he probably judged it a more sensible policy than open persecution , and a way to distinguish himself from the " great persecutor " , Galerius . Constantine decreed a formal end to persecution , and returned to Christians all they had lost during the persecutions . 
