It turns out that in Pompeii, they used to mark the road with “arrows" directing men to the nearest brothel. There are several of these throughout the city. I like to call them pompenises.
too soon
IT WAS NINETEEN HUNDRED YEARS AGO
but when I went there the guide said it was pointing to a toilet where men could pee. He even showed us the toilet section where they went :E It was only a small room. Not enough room for a bunch of prostitutes.
I HAVE PHOTOS AND SHIT SOMEWHERE.
I saw these too. Apparently the penis was also a sign of welcoming.