The first-century natural philosopher Pliny the Elder, in his "Natural History", reported a tradition, attributed to Aristotle, that the Cyclopes were the inventors of masonry towers. In the same work Pliny also mentions the Cyclopes, as being among those credited with being the first to work with iron, as well as bronze. In addition to walls, other monuments were attributed to the Cyclopes. For example, Pausanias says that at Argos there was "a head of Medusa made of stone, which is said to be another of the works of the Cyclopes".