Will
The place to go is the boulder at Clifton moor York. While it’s not real rock, there is a kids playground, a nature trail, mini mountain bike trail and the main East coast railway line.
I took my grandson there, he allowed me help him climb so I could take a picture. He then went on the swings etc, but when he saw the trains go past every few minutes. He was mesmerised, we were only allowed to leave due to hunger and pending darkness.
So a bit of negotiation “if you sit and play nicely while daddy climbs we can then go and watch the trains”