The most uncomfortable, narrow, steep, small steps, no windows and no landings was definitely the one at the Voortrekker Monument in Pretoria. I'm not sure how many steps and exactly how high, but I assume it's about 30m to 40m all in one go. Very narrow at 600mm, the steps at the outside is 200mm and the inside a mere 100mm, and the height a hefty 200mm! Down is just as bad as up, especially for adults. You have to keep close to the outside wall as your feet don't fit!
I paint only the outside walls transparent, so that a person can see the inside. Measurements are correct as far as I can remember. Did not have a measurement tape at hand.