Both his adoptive surname, Caesar, and his title Augustus became the permanent titles of the rulers of the Roman Empire for fourteen centuries after his death, in use both at Old Rome and at New Rome. In many languages, Caesar became the word for emperor, as in the German Kaiser and in the Bulgarian and subsequently Russian Tsar (sometimes Csar or Czar). The cult of Divus Augustus continued until the state religion of the empire was changed to Christianity in 391 by Theodosius I. Consequently, there are many statues and busts of the first emperor.
The adoption of Caesar's surname and title, Augustus, as permanent titles for Roman rulers lasted for fourteen centuries after his death, used both in Old Rome and New Rome. The cult of Divus Augustus persisted until Christianity became the official religion of the empire under Theodosius I in 391 AD.