Nice Old Town (known locally as Le Vieux Nice) is a lovely honeycomb of narrow streets, dotted with beautiful Baroque churches, vibrant squares, shops and restaurants. Thronging with tourists eating the famous ice-cream during the day, at night it becomes one big party with bars and nightclubs spilling out onto the streets.
The key things to see are the Cours Saleya (the open air market), Chapelle de la Miséricorde (a wonderfully ornate Baroque church dating from 1740), Chapelle de l'Annonciation (known locally as Sainte-Rita), Eglise Saint-Jacques (dating from 1612 and built by the Jesuits, it has some excellent frescoes), the Cathedral Sainte Réparate (1699), and the Palais Lascaris (paintings and statues).
Nice Old Town in located between the seafront of Quai des Etats-Unis and Boulevard Jean Jaurès. The main bus station is a short walk away.