Certaldo Alto is the reason you came. Step off the funicular into a brick-paved medieval town so well preserved it feels less like a tourist site and more like a place that simply never needed to change. The narrow lanes, the terracotta rooftops, the views over the Val d'Elsa vineyards — it is all genuinely, unhurriedly beautiful.
The upper town's two main draws are the Palazzo Pretorio, the fortress-museum that dominates the skyline, and the house where Giovanni Boccaccio spent his last years writing and is now buried. Between these two, and the pleasure of simply wandering the streets, Certaldo Alto rewards an unhurried half-day or a full one if you linger over lunch.