If you're curious about the Crusades, this lecture from professor Thomas F. Madden sets the stage for what became a 400 year war between Christians and Muslims over the Holy Land and between competing sects within these religious ideologies. This lecture focuses on the history of Christianity from its humble beginnings to its rise to prominence in the Roman Empire with the conversion of the Emperor Constantine, the development of the Papacy, and the formation of the Byzantine Empire. It's an informative lecture covering a lot of Christian history from the time of Christ to the start of the First Crusade in the 11th century.