Rome by 600 AD is no longer the "City of the Caesars" : while most of its palaces or monuments, even if transformed or re-used, were maintained until the Gothic Wars, they were devastated during the conflict. Aqueducts are gone, the walls are ruined, palatine houses abandoned and the economic heart gone into flames when they didn't collapsed or burnt in 552 as Totila (according to Procopius) ordered the city to be set on fire before Imperials could take it again.

This isn't just the result of the material destruction and the regular sieges of the city, but as well the disappearance of the former ruling classes : while senatorial elites not only survived the theoretical fall of the Roman state but even blossomed under Ostrogoth rule, and while clashes weren't unknown even at the end of Theodoric's reign; the wars sharpened the contradictions and perceived threats or treacheries : Italian senators were taken hostages, executed, etc. The social trauma on a late ancient society that was the main backing and founding of the maintain of Rome as it was since the Late Empire, trough what is sometimes called euregetism, basically how nobles and noble families used their private wealth to fund public service, building (or repairing), etc. but as well their own private display of prosperity such as rich housing and palaces.

And as Lombards advanced in Italy, Rome became sort of a secondary frontier town directly threatened by the late 570's, and on which Popes had much more importance they ever had before.While the city was unmistakably damaged and "exhausted" to quote Maya Maskarinec, popes themselves lamenting over its ruin, it didn't collapsed : fifty thousands citizens still lived in Rome by the early VIIth century, but the city was importantly transformed.

On the ruins of forums and in place of disappeared palaces, churches, cemeteries, monasteries and basilicas were erected; the senatorial families didn't disappeared; even if they certainly suffered, but "reconverted" into ecclesiastical careers not only lending their wealth to the Church but transmitting it and making her the main landowner in the city and the region.

Not that all monuments were ruined either : if they were damaged, some were still hastily repaired or the high technicity of their construction allowed them to remain largely dominant, such as the Coliseum which was nevertheless used as a quarry since the VIth century.

Rome was still able to pay for important power displays, always from then associated with Papacy, such as gathering enough coins to send as tribute to Constantinople (in order to pay for soldiers to defend the city) or processions on a grand scale to welcome the imperial presence (only real in the case of Constans II, but generally to welcome the remote presence of the emperor as for Phokas). Similarly, the public charity and food distribution was now made and overseen by the bishop of Rome, in place of the former imperial service : not a radical change of power, but rather a new delegation.

As a traveler, you might notice an important display of piety and if you were sent for any business, political or otherwise, you'd have to deal with clergymen, papal delegates, if not the pope himself if you were someone important. Before 600, there was probably not a particular imperial officer responsible for Rome, the pope even acting as an autonomous ruler under imperial suzerainty, and able to command military officers (without necessarily being obeyed) to not follow the exarch's policy, even expanding his secular power beyond Rome itself.

As such, in 600, a truce was found between Gregorius and the Agiulf in 593 (while a peace was settled with the exarch Romanos only in 598) and you'd be entering a relatively safe city as the threat of a Lombard siege was over for the moment. It seems that a duke, or a magister militum, was already present in Rome then and responsible of an Imperial garrison guaranteeing both the city and the imperial and exarchial authority : it's possible that Romans kept the distinction between civilian and military command that were fused elsewhere in the western provinces since the Vth century, and in Italy since the Imperial reconquest.

What the city looks like for you as you enter it? A mix of ancient monuments, more or less damaged or ruined, and modern religious monuments which marked the territory and claimed a new precedence in the order of things. It would only be after some years that the Pantheon would become a church and even more for the Senate being so as well, tough and if Rome wasn't made in a day, neither was she re-made as

[...]the clamor of daily life is much stronger, and with the vegetable sellers and grumbling fishermen it takes effort to remember that this is a sacred city. Only if we are attentive does this world of sanctity emerge.

The low-lying plain of the Campus Martius where we have entered the city is an especially dense thicket. Without any hills from which to regain perspective, we can quickly get lost in the maze of little streets, losing any orientation. A lone cypress tree can serve as the most reliable signpost. Aristocratic dwellings front the more prominent roads, but if we duck into the neighborhoods we find smaller ramshackle houses and heaps of trash among the large tufa blocks of ancient monuments.

( City of Saints ; Maya Maskarinec)

Basically, by going to Rome in 600, you come to a city that's changing before your eyes, from the memory of the ancient head city of the Empire to a modern head city of Christiendom : not everything from the first disappeared or is yet transformed; but soon after your journey, it would have been.

- City of Saints, Rebuilding Rome in the Early Middle Ages; Maya Maskarinec; 2018

- Le duché byzantin de Rome. Origine, durée et extension géographique; Bernard Bavant; 1979

- Roma capta, Il sacco della città dei Galli ai Lanzichenecchi; Umberto Roberto; 2012 (french edition, translated by Yann Riviere).