This is a serranda (pl. serrande). It’s kind of like a metal gate and shopkeepers use it to stop miscreants from pulling off heists and other felonious capers of an evening. This particular serranda makes me sad because it means my favourite granita spot is closed for the summer (but only for a few days more!). Usually, the serrande around Rome look like this.
But lately they’ve started to look like this.
Pretty great, eh?