Wikipedia entry on the Byzantine Empire

Wikipedia has an excellent entry on the Byzantine Empire. In scope it covers the time from the unified Roman Empire through the split up to the dissolution of the empire during the time of the Crusades. I very much enjoy the coverage of the strategies employed by various leaders to hold and expand the empire, including the interesting thema system used to expand, settle, and militarily hold onto territory. Also of great interest is coverage of the interplay between religion and politics in the eastern and western portions of the Roman empire and in the crusades and ultimate end of the empire.