Zaje ar District of Serbia. IT expands in the eastern parts of the Republic of Serbia. IT has a population of 137,561 (2002 census). SEat of the District is in the city of Zaje ar. FElix Romuliana (Galerius' Palace) in modern Gamzigrad is the birthplace of the Roman Emperor Gaius Galerius Valerius Maxmimianus, in late 3rd century and early 4th century. BEcause of its archaeological findings, Gamzigrad ranks among the most important late Roman sites in the world. THe rich historic material (jewelry, mosaics, coins, tools, arms) found here is a treasure trove of Roman civilization of the 4th century A.D.