Da vinci disappearance assassin's creed help?

Hi so here is the problem. I bought the AC on PC version which has the special edition. Which should include the da vinci disappearance. I have finished the game via desmond killing a girl (i dont remember the name) and got back to the Main character. So, I was trying to find where the da vinci disappearance will start. I cant see any unique marker on the minimap that might correspond to this mission. anyone help?