In reply to leobold:
Last year I was on a road trip with (non-climbing) family so I couldn't stop to check out the walls, however, I did spot nice big ones to the east side of Crete. The walls were on the left of the motorway 'EO Iraklio Agiou Nikolaou' (I think!) when you drive from Selinari to Agios Nikolaos. If memory serves correctly, there is an archeological site (settlement?) on the far right of this motorway (although just past these walls and closer to Agios Nikolaos). I was under the impression at the time that it was a gorge (although I may be wrong), particularly. I'm sorry I couldn't be more specific about the location, maybe if someone has been in the area this description will jog a memory?
If we could include photos I would put one up so you could judge the approximate height as my multi-pitch experience is non-existent. From memory, it won't be many pitches, I can't imagine more than two/three. Let me see if I can find that photo and link you to it somehow.
Fair warning (lecture imminent, sorry!) Crete is fairly easy to drive using the coastal roads. Under no circumstances though, should you drive in the mountains or get stuck in it right before/during nightfall. They don't have lights, the corners are dangerous (you'll notice the "death/mourning" posts on almost every corner) and the locals drive like they own the mountain (to be fair, they probably do). It's actually a benefit if you have a narrow-ish car.