Mount Buninyong is a small extinct volcanic cone, 745 m above sea level and about 15 minutes south of the city by car, with a near-perfect crater you can walk down into. A sealed road climbs to the rim; a short bushwalk loops around the top with views back to Ballarat, west to the Pyrenees, and on clear days to the Otways and the You Yangs near Geelong.
A picnic ground, a fire-lookout tower (climb it for a wider view), and the start of a longer trail down to the village of Buninyong. About an hour all up. Best in late afternoon for the light.