Complex sentence: The Naubatkhana was in such disrepair during the last century that the American Mission declined to take it as a gift, and then it was restored by George Fisher in 1858 for the new Zilla School.
Split into simpler sentences: The Naubatkhana was so dilapidated during the last century that the American Mission declined to take it as a gift. It was then restored by George Fisher in 1858 for the use of the new Zilla School.