The cognomen "Iustinianus", which he took later, is indicative of adoption by his uncle Justin. During his reign, he founded Justiniana Prima not far from his birthplace. His mother was Vigilantia, the sister of Justin. Justin, who was commander of one of the imperial guard units (the Excubitors) before he became emperor, adopted Justinian, brought him to Constantinople, and ensured the boy's education. As a result, Justinian was well educated in jurisprudence, theology and Roman history. Justinian served as a "candidatus", one of 40 men selected from the "scholae palatinae" to serve as the emperor's personal bodyguard. The chronicler John Malalas, who lived during the reign of Justinian, describes his appearance as short, fair skinned, curly haired, round faced and handsome. Another contemporary historian, Procopius, compares Justinian's appearance to that of tyrannical Emperor Domitian, although this is probably slander.