DH thinks the DCs are now old enough to go to the park alone (9 and 7) but I'm not convinced. We have a big park almost opposite our house but they would have to cross a road to get there. It's not fantastically busy except at rush hour and they're pretty reliable road crossers. But then I worry that if something happened at the park - if they fell out of a tree, or into the stream or off the swing or something - and they hurt themselves, what would they do? What if they got lost or someone kidnapped them? The last two are unlikely I know but I don;t think I'd have a moment's peace while they were out!
It's funny, I'm sure when we were kids we roamed all over the place by ourselves but I feel much more nervous about my DCs doing so!