The 13th-century town hall on the Piazza del Duomo is the seat of civic power that never really changed hands. Construction began in 1288 and the building still serves as the municipal offices. Inside, the Museo Civico occupies the upper floors, with a collection of Sienese and Florentine paintings — the Maestà by Lippo Memmi is the centrepiece — and a frescoed Sala di Dante, where the poet addressed the town's council in 1300 as Florence's ambassador.
The Torre Grossa rises from the palazzo to 54 metres — the tallest of the surviving towers and the only one open to the public. The climb (218 steps) is straightforward, and the view from the top is the best in town: the full sweep of towers below, the Tuscan hills rolling away in every direction. It is included in the Museo Civico ticket. Get there early to avoid a queue on the narrow staircase.