Hi, I just got past that point and am stuck in the library myself. If you jump from the one rooftop to the balcony, from there keep going to the next one. Then when you are on the last you can save and jump back towards the way you came. When on the roof, I just walked quietly and carefully to the chimny, went up close to the fence and jumped to the chimney and climbed in. Actually once on the roof it isn't to hard.