Philip II (r. 1180–1223) began the conversion of Paris into a capital befitting the growing power of France. The city walls and fortress of the Louvre were both commenced in 1190. Completed in 1220, the walls encompassed ten gates and 75 watchtowers: the security they afforded encouraged the rapid commercial development of the right bank, with the main port at La Grève. The royal palace presided over the growing metropolis from the Île de la Cité, alongside the cathedral of Notre Dame. The maintenance of order was the responsibility of the Royal Provost, housed in the Grand Châtelet beside the Grand Pont, the larger of two bridges, together linking the banks via the Île. Radiating from Notre Dame, a network of abbeys (including St-Germain-Des-Prés) made the left bank a centre of learning. Beginning with Abbé Suger (1080–1151), Paris’s churches established the vogue for Gothic architecture and stained-glass windows.