Complex sentence: It is the traditional heart of the M'zab valley, home of the Ibadi sect in Algeria, and has preserved its original medieval architecture remarkably well; the valley of which it forms a part is an official World Heritage Site.
Split into simpler sentences: It is the traditional heart of the M'zab valley, home of the Ibadi religious sect in Algeria. The residents have preserved the original medieval architecture remarkably well; the valley of which it forms being a part of an official World Heritage Site.