Rotundus was vogt of Vilnius, general secretary to the Grand Duke and King Sigismund Augustus and elder of Stakliškės.
Undoubtedly Rotundus was a passionate catholic after graduation and supported Hereditary monarchy and Execution movement.
Augustinus Rotundus died on 20 March 1582 and was buried in the church of Saint John's - the Baptist and Evangelist, in Vilnius.
In this study Rotundus promoted the idea, that Lithuanians together with their Dukes have roots in the ancient Roman Empire, from the mythical house of Palemonids.
He claimed that Publius Libonus, Roman commander who fled from Julius Caesar and supposedly settled down in Lithuania, was ancestor of Lithuanian and Ruthenian rulers.
[6] In 1564 on personal request by Mikołaj "the Black" Radziwiłł Rotundus wrote Rozmowy Polaka z Litwinem (Conversations of Pole with Lithuanian) – a polemic work, where he defended Lithuania's dignity against insults by Polish author Stanisław Orzechowski in Quincunx (1554), "...against disgraceful and mistaken Stanisławs Orzechowski writing, which innocent famous Lithuanian Duchy insulted...".