I tend to prefer markers to not having them. In some games it's ridiculous ("Find the hidden treasure! I'll just mark it on your map...) but having well-know places marked for you makes sense. I'd just assume that the source hunters got a map of the city at some point.

"But I don't want to go among mad people."
"Oh, you can't help that. We're all mad here. I'm mad. You're mad."
"How do you know I'm mad?"
"You must be, or you wouldn't have come here."

Public Key ID: 057420A1