The Adobe office in San Jose had people who came in to take care of the plants; they skulked around in the shadows, careful not to make eye contact with anyone. Not so in Hamburg; the plant guy makes his way into and out of the office each week with a loud "HAAAALOOO!" and "TSCHÜSS!!", and his greetings are returned just as loudly. When you go shopping, it's customary to exchange a hello-and-goodbye with the store clerks. Pretty often I worry that somebody will think me rude -- or stupid -- because I didn't exchange greetings with them, or forgot to say goodbye ...
To bring this back to Hamburg, there's supposed to be an interesting English-only bookstore near the University; we'll have to go check it out sometime soon.