Lovely photo. Yes, for sure it's hot under there!! But what a photo op it would be!
If you do manage to get in from the outside up there watch out for that first step. It’s a doozy.
I remember a view of the interior construction of the cupola at Vaux-le-Vicomte. Something like this. Perhaps there is a similarity in construction with these cupolas. Access would probably be about nil here, however.
Thanks, merci, grazie, danke, hvala, gracias, spasibo, shukran, dhanyavaad, salamat, arigato, and muito obrigado for your much-appreciated comments.