Angers is compact enough to walk between the main sights. The château, the cathedral, the Ensemble Saint-Jean, and La Maison d'Adam form a tight medieval cluster on the left bank of the Maine, all within ten minutes on foot. The city's tram and bus network (Irigo) covers the wider urban area and is reliable Monday to Saturday until around 20h; Sunday service is limited enough that you are better off walking or cycling.
Cycling is well-suited to the flat terrain. Hire bikes are available through the city's Vélocité scheme from docking stations near the train station and the château. Taxis tend to queue at the Angers-Saint-Laud railway station rather than circulate — if you need one away from the centre, call ahead or use a booking app.