I was watching a Rome documentary when they were talking about the fire during the reign of Nero that destroyed a large part of the city (and was believed to have been set by Nero himself). My understanding of Roman architecture is that they used a lot of stone, so I’ve always had trouble wrapping my mind around how such a stony city could burn so readily.
I imagine they had enough tinder lying around in the form of carts, barrels, hay, etc. but I still don’t quite understand how stone structures would sustain massive structural damage and continue to feed a giant fire like that. If it was indeed arson, of course the setter(s) could help it along with multiple points of origin and the spreading of tinder, but I’m still having trouble wrapping my mind around it.
And even buildings that have stone walls are still full of flammable objects, and usually the roof is flammble thatch or shingles. Even roofs of slate or tile are usually held up with big wooden beams.
Well when they talk about the marvelous feats of Roman engineering and architecture - the Pantheon, the palaces, the aqueducts, the baths, the forae… it’s all stone. I suspected there might have been wooden houses but that’s not something they talk about very much in Rome documentaries.
Serious fires were common in large cities then, and for centuries afterwards, and there was little effective action taken to mitigate them.
While the foremost public buildings were stone, most of the common people would have lived in firetrap tenements.
The Emperor Augustus was famously reported to have said, “I found Rome wood and left it marble.” He was, of course, talking of the center of the city. Much of the suburbs would still have been shanty built of highly inflammable materials. The same was true of London some 1700 years later.
"Who at cool Praeneste, or at Volsinii amid its leafy hills, was ever afraid of his house tumbling down? Who in modest Gabii, or on the sloping heights of Tivoli? But here we inhabit a city propped up for the most part by slender flute-players: for that is how the bailiff patches up the cracks in the old wall, bidding the inmates sleep at ease under a roof ready to tumble about their ears. No, no, I must live where there are no fires, no nightly alarms. Ucalegon below is already shouting for water and shifting his chattels; smoke is pouring out of your third-floor attic above, but you know nothing of it; for if the alarm begins in the ground-floor, the last man to burn will be he who has nothing to shelter him from the rain but the tiles, where the gentle doves lay their eggs.
It’s also worth mentioning that many of these insulae were five stories high (or more), and built shoddily enough that the outer walls leaned perceptibly. A person walking through an alley between two of these buildings might look up to find the topmost stories touching. As a result, fires spread easily from one insula to the next, and rooftop blazes, already the most difficult kind to put out, had the potential to wipe out whole city blocks.
One of the stories told about Marcus Crassus is that he would show up at the scene of a fire with his personal fire brigade. On the spot he would offer to buy the building from the owner – at a ridiculously low cost, of course. If the owner agreed, the fire brigade went right to work battling the blaze. In not, Crassus would wait patiently until the damage had gotten worse, then make another offer, significantly lower than the first. By this process, he accumulated properties all over the city and became at once Rome’s greatest real estate tycoon and its master slum lord.