Pisa sided with the Normans in Sicily and profits from its new commercial empire in the western Mediterranean paid for its magnificent cathedral, baptistery, and campanile (today's Leaning Tower).
The Normans were enemies of Pisa, he worked to overthrow them.
mnli hypothesis: The Normans were enemies of Pisa, he worked to overthrow them. premise: Pisa sided with the Normans in Sicily and profits from its new commercial empire in the western Mediterranean paid for its magnificent cathedral, baptistery, and campanile (today's Leaning Tower).