Mithras worship
When the cult developed in Rome, and became prevalent through much of its empire, the statuary shows the cap as an iconic part of the god's costume as he kills a bull, the killing being part of the centre of the mystery. The worship was inspired by a much older Zoroastrian cult in Persia and its predecessor. It lasted in popularity until the end of the 4th century CE. It became seen as a rival to Christianity and eventually was suppressed and then eliminated in the Roman empire. The Phrygian cap is a soft conical cap with the apex bent over, associated in antiquity with peoples in Eastern Europe and Anatolia, including the Balkans, Dacia, Thrace and Phrygia. Much later the cap came to be a symbol of freedom and the pursuit of liberty, first in the American Revolution and then in the French Revolution.