Room was nice, and breakfast was fine. But had a very unpleasant memory at the end. When we came back to the hotel, we found out that the room was not locked with windows wide open. We asked the front desk to check, and they promised to get back to me after talking to the manager. However, they said nothing - we asked twice, at night and next morning - and just murmured it must be room cleaning staff who forgot to close the door at the end when checking out. We felt very unsafe while sleeping, and could not hear anything but simple sorry. Made all the good memories in Vienna bad.