Olisipo, like most great cities in the Western Empire, was a centre for the dissemination of Christianity. Its first attested Bishop was St. Potamius (c. 356), and there were several martyrs killed during persecutions, such as the Diocletianic Persecution; Verissimus, Maxima, and Julia are the most significant names. According to legend the three were sons of a Roman senator, martyred in Lisbon in the 4th century, under the Roman governor Ageian or Tarquinius in the time of Emperor Diocletian. A temple was then built in the Campolide area, whose ruins still existed in the Middle Ages.