Although a little "sensational" in tone, view these brief clips with the notion of "decline" in mind. Also note the roles of Clovis, Monastaries, and St. Benedict.
Below are two brief clips focusing on the disastrous Fourth Crusade, where the Christian city of Constantinople was sacked by the Crusaders.
The ubiquitous Michael Woods on the Romanesque, Pilgrimmage, Monastaries, and the Gothic.
The clip below focuses on the earlier Romanesque style, but also note the importance of holy relics and pilgrimmage in the 11th and 12th Centuries.