24 hours! Just ring the bell by the window. Have your pal or whoever is with you keep an eye on…read morethe sketchy dude and run some bluster if he comes your way. What do you expect at midnight on a street corner in Prague (or any major city for that matter) while standing at a window seeking drugs? A life saver while we were visiting Prague. Nothing solidifies your travel experience in a new country like a late night hospital visit followed by a 24 hour pharmacy window...that's what I always say.