Any character can do it (although i only realized it by accident when my Necro was about to start it, a Ranger asked me to do the quest with him

)
A short info about the Cities of Ascalon Quest.
1. Symon the scribe can be found is Ascalon. Go to Tydus and find the stairs that will bring you to Northern Wall. Facing the wall with dragon, turn left and go down. You'll find Symon.
2. You'll be asked to find 3 markers. The first two are easy to find but the other one can only be accessed doing the Ruins of Surmia mission (your first mission with Rurik). The marker is located in the entrance of the ruins (before you open the gate for rurik).