Obviously the city was raided but in all of my history classes, I've never heard what happens to Rome until the 15th century.
I go through this topic extensively in the below link.
In a nutshell, the city of Rome suffered something like a 75-90% drop in population following the 6th century Byzantine reconquest, which resulted in an almost complete break with its classical past.
However, despite this chaos, it still remained one of the largest cities in western europe up until the 10th century, and never lost its place as a prime pilgrimage destination.