How long does it take to hike to the bottom of the gorge in Ronda and back?
 

Obviously, it depends on one's hiking speed but wondering if this is more a one hour activity or a 5 hour one.

Also, is the trail always open or does it close at a certain time in the evening?

I think there are a few options taking different amounts of time. We went down the old mine - 281 steps down and UP again. That took about an hour. We walked down a path as well, again, about an hour to an hour and a half round trip with time for pictures. There looked to be some longer paths as well, but I can't comment on time though. My guess is no matter which route you take, nothing should be more than a 2 hour round trip, with leaving time to take pictures.

Like debinthepeg, I took the mine route, down and up in under an hour.

I took a 3 hour sunrise horseback ride of the gorge. The owner picked us up at the hotel then dropped us back after the ride. Haven't been able to find if he is still open but maybe a hotel in Ronda could help you out. We found his brochure at our hotel's front desk but that was 15+ years ago.