Our closest metropolis, here in western New York, Buffalo, is proud of its botanical gardens, which I've just visited for the first time. I'd never seen them but had driven past, remarking on some slight similarity with Kew.
When I was about six year's old I stroked someone's pet cactus because it looked furry. I'm still pulling the spines out. Despite that, I never really understood the fascination before but I think I do now.