Rome has lots of people, lots of old buildings and lots of heat in August.
Despite that, you can wander the vias (streets) relatively coolly as many buildings are tall which makes the pavements quite shady and of course you can cool yourself down at numerous cafes and gelerati bars.
However beware the sharp shoppers, as I was minding my own business moving from side to side as I passed tourists, locals and serious shoppers on slim pavements. ……..a seriously sharp posh carrier bag was wedged under my armpit by a passing lady…did I say lady? But she carried on walking as I was being hooked up by the very sharp corner of her very posh carrier. ……until I managed to unhook myself, she didn’t bat an Italian eyelid or pause for breath as she bantered with her beau.
I survived albeit a bruised armpit glowing under my newly acquired tan.