At one stage there were dozens of these cast iron Octagonal Cafés in Berlin, but they were for men only and had a bit of a smelly reputation. This one was renovated and opened in June 2003 in Gendarmenmarkt Square. It is now for both sexes with modern facilities though it is compact inside, but unlike other public conveniences in Berlin this one is free.
The second photograph is a Gents only Octagonal Cafe on Schonhauser Allee just outside Senefelderplatz U Bahn Station.
The third photograph is another Gents only Octagonal Cafe close to the Zoologischer Gartený railway station.
The website provides a history of restrooms in Berlin together with photographs.
In a lot of bars and restaurants and also in some shopping malls, there will be an attendant on toilet duty. They set up table outside , sometimes they offer candy/sweets and fruit and they keep the toilets clean. They also like a tip.
Ladies be prepared and carry change. I found at nearly all restrooms you were charged at least DM1 - even out of the city. I don't know if this applied to the men's restroom as well.