Hmmm, ok, so....counting out the squares...people on horses could get into the ruins from the end of cover in a single double move, thereby eliminating the danger of approaching from that direction. So...it all depends on how many of our PC's have got ranks in climb, because if you don't have ranks in climb...well, you're gonna have a bad time approaching from anywhere else. So just off the top of my head, I would say send the people who have ranks in climb to approach from the stealthy routes - whether they hit both or only one depends on how many characters we have that have those ranks - and when they hit and distract the gobbos inside, the rest of the party either throw up hooks from another section of the wall, or charge up the switchback on horseback and get into the fortress before the archers can hit them from the walls (since a horse can move 100ft as a double move in a single turn, and that's roughly the length of the entire switchback).<br/><br/>Risky, but it's the only way of getting the people who don't have ranks in climb into the battle safely without risking them falling to their deaths. :P