Tucked into a steep gully south of the centre, the University of Siena's botanical garden has occupied this site since 1784. Terraces, greenhouses, and beds run down the slope, with sections for Tuscan medicinal plants, succulents, and a small arboretum.
It is a calm escape from the more visited corners of the city, and the elevated paths give unusual views back up at the Duomo's apse. The Diana, a small subterranean stream the medieval Sienese famously failed to find despite enormous effort, is said to run beneath the garden.