This hostel is a good ways from the historic center of Siena, but it's a pleasant walk, and if you like walking like I do, it's no problem! Breakfast is coffee plus donut and/or croissant so if you need your protein like me, make other plans!
For a hostel, this place is incredibly clean, quiet, attractive and safe-feeling. I was a 45-year-old woman travelling alone and I got a second floor room across from the shared bathroom without asking. Even with a window facing a semi-major street I slept well! Facilities are spartan but more than adequate for budget-conscious adventurers. Wifi was fab and Leonardo and Christian were super friendly, helpful and competent! In fact, this place was better than my hotel in Cinque Terre, and was 1/3 the price!