Between the September of 387 and the end of 388 at the earliest, Augustine moved from Milan, to Ostia, to Rome and then to Thagaste, his birthplace in North Africa.
After his baptism by Ambrose in Milan on Easter Sunday 387, Augustine remained there until towards autumn (September).
He continued writing On the Immortality of the Soul and On Music.
Before baptism he had been thrilled with his otium (Latin for "holy leisure" or "free time") at Cassiciacum outside of Milan.
Augustine and his party moved from Milan to Ostia to await passage across the Mediterranean Sea to the port of Carthage, North Africa.
On 13th November 387 at Ostia, Monica died after five days of fever.
Her death and and his own grief are covered by Augustine in Book Nine of his Confessions, where Augustine offered the world one of the greatest passages in all Western literature.
The small group was detained at Ostia. A civil war was raging in the Roman Empire and Ostia, which at the mouth of the Tiber River served as the port of Rome, was blockaded.
To wait out the blockade, Augustine went to Rome for about one year with Evodius, later bishop of Uzalis - his friend who had also been with him in Milan and at the death of Monica in Ostia.
In the fourteenth century there were Augustinian authors who wrote down legends that Augustine did more than visit Rome during the period of the twelve months mentioned above.
In an effort to strengthen the identity of the Augustinian Order as its literally coming from Augustine himself, they promoted legends that variously suggested that he went to Tuscany to experience eremitical (hermit-like) life there, that while there he wrote his Rule for an eremitical community there, that he actually founded a community there, that he visited the (later) Augustinian monastery of Lecceto, that Bishop Ambrose of Milan had given him a religious habit at the time of his baptism, etc.
All of these suggestions are fanciful and incorrect because Augustine's Retractions provide a first-hand report of his presence and activity in Rome. And credence is no longer given to the medieval legend that, as well as live in Rome, he was also in Tuscany but simply forgot to record the fact because of the depth of his grief for his recently-deceased mother.
Ostia. The Harbour City of Ancient Rome