A rather risqué surprise lurks in the street-level loggia (balcony) of a 13th-century former wheat store close to Piazza Garibaldi. The loggia shelters the Fonte dell'Abbondanza (Fountain of Abundance), a now-decommissioned public drinking fountain built in 1265 that features an extraordinary fresco known as the Albero della Fecondità (Fertility Tree). This portrays a tree laden with penises hanging like fruit and shows women fighting each other for those fruits that have fallen.
The 270m-long cunicolo (underground tunnel) along which spring water once flowed to the fountain can be explored on occasional tours led by members of the town's speleological society – bookings are made through the Museo Archeologico.