The Council of Serdica was one of the series of councils (or synods) called to adjust the doctrinal and other difficulties of the Arian controversy, held most probably in 343 AD in St. Sophia Church in Serdica or Sardica (now Sofia, the capital of Bulgaria). It was attended by 316 bishops. It was called by the Roman Emperors Constans and Constantius II at the request of Pope Julius I.