Many of the landmarks that still exist (and of those that don't, e.g. the Septizodium), except for those saved by being directly converted into a church (the Pa

Many of the landmarks that still exist (and of those that don't, e.g. the Septizodium), except for those saved by being directly converted into a church (the Pantheon), saw heavy repurposing as fortifications in the endless and often violent power struggles between patrician families. The Circus Maximus was a Frangipani stronghold. Others (and the Circus Maximus before it was taken over by the Frangipani) were simply saved from getting used as a quarry by getting incorporated in-place as structural elements for new, well, shacks, as documented by the many, many square holes hewn into the formerly flat stone surfaces. Square holes for holding wooden beams I suppose. The (still in use!) appartment on top of the Theatre of Marcellus give an idea of how that went. In this case, they are the outcome of a slow fortress->palace->middle class residential transition.