As an important crossroads Lausanne witnessed the emergence of five neighbourhoods: Cité, Palud, Pont, Bourg and St-Laurent. With its city limits pushed back from the Cathedral (in the 6th century), to Palud and Bourg (9th century) and to St-Laurent (10th century), the city reached its apogee around 1300. The ridge, and the walls, now part of the Old Academy foundations and visible from the Bessières Bridge, testify to the citys defense system.
The Cité concentrated “official” structures such as Cathedral, Evêché (bishop's residence), the St-Maire Castle and the Grand Hôpital. La Palud, down below, evolved into a commercial and political hub with its City Hall. The Pont district grew at the junction of Flon and Louve rivers, now covered. Tradesmen and artisans settled down in the valley to take advantage of the hydraulic power produced by mills, which numbered more than 50 around 1830. On the other side of the Flon Valley, the Bourg became the home of luxury shops and inns. The fortified convent of St-François – whose church remains – formed an outcrop on the citys southside wall. On the other side of the Louve Valley, artisans flocked to the St-Laurent district. Its face was profoundly modified when new streets were opened in the 19th century.
The Ale Tower and that of Ouchy's bishop's castle (12th century) are the last remnants of some 50 towers which made up the citys medieval fortifications.