18th Century Do Not Litter Sign
It appears to be a 18th century do not litter sign.
'Di ordine di monsig Illmo Rmo Presidente Delle Strade Si Proibisce ad ogni persona di gettare e far gettare in qvesto vicolo immondezze di ogni sorte e farvi il mondezza ro sotto pena di scvdi dieci oltre i altre pene ad arbitrio di sva sigria illma comminate nell editto pvblicato li XV Aprile MDCCLXIV AL Qvale'
Transalated via Google as: 'By order of Monsign Illmo Rmo President of the Streets It is forbidden for every person to throw and throw in this vicious alley of every sort and make you the end of the world under the punishment of ten more than the other punishments of arbitrary minds of all the illusions of the edict proclaimed 15 April 1764'
Submitted by: @IanThorp