Where: Castle Climbing
It may look like a castle from the outside, but this magnificent Victorian Grade II listed building was once upon a time a water pumping station. Nowadays it is known as the premier indoor climbing centre in the south east of England, and is open to climbers who can choose to either rope-climb up the building or abseil down the walls. No experience is needed, and it's open seven days a week. You'll find it right by Finsbury Park.