Riniasa Castle protected the medieval city of Riniasa (near Riza village) from a naturally fortified rise, keeping watch over land and sea trade. It is believed to have been built by the Despot of Epirus Thomas I in the late 13th century, and was for this reason called Thomokastro.
During the 1338 revolt against Byzantine rule the castle was governed by Nikephoros, son of the last Despot Orsini. John Kantakouzenos persuaded him to hand it over, and the Byzantines held it until 1350, when it passed first to the Serbs and then to the Albanians, who named it Riniasa. It came under Ottoman control in 1451. In 1803, after the sacrifice of Despo Botsi, the castle was briefly taken by the Souliots, to be abandoned completely after the Greek defeats at Peta and Plaka.
