I recommend the Singer Hostel to travellers who are on their own or small groups of people. I had a nice stay there and met people from different countries (Bulgaria, Croatia, France and even some funny Englishmen:D). Everyone was nice and the staff was helpful and friendly. The room was very clean and the highlight is definitely the lounge, which is very welcoming and comfortable to even spend some hours in the evening having drinks and conversations. The Alexanderplatz is only two metro stations away. If I visit Berlin again I will come back here. Thanks a lot!