Assassin's Creed Brotherhood An Apple A Day (Full Synch)
Full synchronization guide to the mission "An Apple A Day". You cannot kill anyone (yes, absolutely no one) to meet the Full Synch requirement. Detection by guards will not desynch this mission so don't worry. Once you reach the outside of the Castelo, a 4 minute timer begins and all guards will turn hostile towards Ezio and active hunt for him, so hiding will not remove the hostility. Keep running along the rooftops for the best chance at reaching the courtyard. Once you arrive at the courtyard, you may need to use a smoke bomb or two to make yourself Anonymous in order to complete the mission.