Rome was a very big city for the time but I've never heard of how they treated their dead. Were there burial sites within or near the city? Did they have catacombs like in Paris? Did they practice cremation? All of the above? Something else entirely?
And just to tack on something else if anyone feels like answering it, did other cities within the empire dispose of their dead in the same way?
In pre-Christian Roman society, the dead were always kept outside the walls of the city. The Romans usually burned their dead, but the rich would construct mausoleums or erect large memorial epitaphs along the major roads. Effectively, people wanted to be as far away from dead bodies as possible.
This changed with Christianity, and this is when the dead started being buried within cities.
For a discussion of this transformation, see:
Brown, Peter. The Cult of the Saints: Its Rise and Function in Latin Christianity. Haskell Lectures on History of Religions 2. Chicago: University of Chicago Press, 1981.
Brown, Peter Robert Lamont. The Body and Society: Men, Women, and Sexual Renunciation in Early Christianity. Columbia Classics in Religion. New York: Columbia University Press, 2008.
The Romans would try to move the dead out of the city as quickly as possible in most cases. The upper class, though, would often have large parades and travel through populated sections of town as the body was carried out of the town.
A good read regarding the daily life of a Roman is:
Shelton, Jo-Ann. As the Romans Did: A Sourcebook in Roman Social History. New York: Oxford University Press, 1998.