An ancient hat made of various materials, commonly leather, felt or fabric. It is generally characterised by an elongated cone shape, in other forms it is oval or a simple dome, as in the case of Ulysses in the scene depicted in the mosaic of the Villa del Casale. Its highly elongated cone shape, with or without the appendages descending on the neck and cheeks, can be traced back to the Phrygian cap or tiara.
The pileus was a popular cap, widely used in various regions, and did not vary greatly over time. In later periods, from the Middle Ages onwards, its most elongated form with precious decorations was used as a prestigious hat.