Massif occidental (westwork)

Préroman (Pre-Romanesque) churches from the carolingien (Carolingian) and ottonien (Ottonian) periods were often provided with an eastern as well as a western chœur (choir).
The picture shows the indeed rather massive narthex (and massif occidental) of the Saint-Philibert in Tournus.
The high part between the towers houses the chapelle (chapel) Saint-Michel.
See also Westbau and Westwerk (both synonyms).

Saint-Philibert - Tournus