On the eastern exit of town heading for Lloret de Vistalegre (the Ma3220), this museum is housed in a cactus-fronted former mill and explains the history of the Son Fornés talayot (watchtower), inhabited from around 900 BC to the 4th century AD. The talayot is one of the most important on the island and easy enough to visit. Head 2.5km northwest out of Montuïri on the Ma3200 towards Pina and you'll see it to the right (east) of the road.
Three-hour guided tours of the museum, talayot and mill can be booked by calling ahead; prices depend on group numbers.