 Flavius Valerius Constantinus , as he was originally named , was born in the city of Naissus , ( today Niš , Serbia ) part of the Dardania province of Moesia on 27 February , probably c . 272 AD . His father was Flavius Constantius , an Illyrian , and a native of Dardania province of Moesia ( later Dacia <unk> ) . Constantine probably spent little time with his father who was an officer in the Roman army , part of the Emperor Aurelian 's imperial bodyguard . Being described as a tolerant and politically skilled man , Constantius advanced through the ranks , earning the governorship of Dalmatia from Emperor Diocletian , another of Aurelian 's companions from Illyricum , in 284 or 285 . Constantine 's mother was Helena , possibly a <unk> woman of low social standing . It is uncertain whether she was legally married to Constantius or merely his concubine . It is unclear if Constantine could speak Thracian , his main language being Latin , during his public speeches he needed Greek translators . 
