The man in front of us used a cane, and he was quite worn out/winded by the time he made it down all the steps after the concert. First you must go up steps outside the fortress. They do have a railing, but it’s at least 1.5 flights. Once inside, it’s almost another 2 flights of stairs to get to the concert area, and it’s through turrets. I think there was a railing. I’m not sure about the public transportation part. We walked from the main bus stop (but we are ages 28 & 30, so keep that in mind :) ). Once you get to the tram entrance, that will take you up to the fort (and the stairs are after that). The tram entrance is in the old town at the base of the fort and the ticket for it should be included with your concert ticket. I hope this helps!

We ate dinner before the concert. And it was a gorgeous restaurant with view. There was a bar too