This little wine cellar, down the stairs to the right as you enter the courtyard, is not retro, it’s real. Descend, rub your eyes and try some of Germany’s finest wines (per glass €2.50). They don’t serve food (other than snacks) but you can bring your own and picnic atop an upturned barrel. A good place to meet real Frankfurters. Situated in Alt Bornheim, 2.