During work for the construction of a large industrial installation in the locality of Ponterotto, San Casciano in Val di Pesa (FI), the remains of ancient structures emerged at opposite ends of the construction area. No archaeological evidence had previously been noted on the site. The first remains identified, situated to the south-west, were those of a rectangular late Hellenistic dwelling (2nd century B.C.). Only the dry-stone foundations were preserved to a maximum height of 40 cm and parts had been robbed. It was not possible to suggest the nature of the standing walls as no unbaked clay blocks or bricks were recovered. In fact, this may have been a hut with earth walls and roof made of perishable materials. The materials from this area were few and of poor quality, mostly found in a midden. They comprised vessel fragments in coarse buff ware, late black glaze ware, grey ware, plain ware, semi-depurated and impasto ware, confirming that this was a rural dwelling. The absolute date of the 2nd century B.C. was also confirmed by a coin find, a bronze as showing a ship’s prow. The other complex, found at the north-eastern edge of the construction area, was part of the _pars rustica_ of a Roman villa, probably of mid Imperial date. Unfortunately, most of the rooms that had probably existed were eroded away in antiquity by a large watercourse. This has filled the eroded part with river gravel so that the preserved structures have taken on a “U” shape. The walls were certainly robbed in antiquity. The presence of postholes, containing a few fragments of Renaissance pottery, suggests that the bases of the walls were used for the construction of huts in perishable materials supported by wooden posts. The foundations, built in large cobbles bonded with mortar, were preserved below floor level. A small patch of _opus signinum_ floor survived in a point where it was protected by a large slab of pietra serena, probably the base of a press. No other floor surfaces were preserved. The standing part of the walls was probably brick-built, as suggested by a section of collapsed wall found in the abandonment layer. At present, it is not possible to provide a precise date for the structure, given the scarcity of dating material; an antonianus of the emperor Aurelian, found in the abandonment layer, constitutes the _terminus ante quem_.