I stayed at 4 hostels while visiting Prague. This was in my opinion the best place out of all. Just bring ear plugs, it gets hot in the Summer so its better to have the windows open and it gets noisy.
Hostel is located in Nerudova street, directly on the famous Royal Route, which winds through the heart of the historical centre of Prague. It is intended primarily for young travellers. Rooms on the top floors and a roof patio offer unforgettable view of the Prague Castle and Petřín Hill.