@charlotte I don't use OSM directly but Mapy, the local Czech map app, is based on it and it is very good for walking. I did review some of my favorite haunts in Prague and my local neighborhood and all the little paths i know are on there. The city seems to be quite meticulously cataloged
@charlotte if you like vistas and don't mind climbing a hill, Petřín is absolutely stunning at any time of year and if you go down the back side you end up near the castle.