There are many watchtowers at key points on the entire island and they date back to the Hellenistic period approximately (3rd-2nd century BC). These towers were used for defensive purposes as watchtowers. On the book of archaeologist Mrs Lila Marangou “Archei Pyrgi” there is a map with the 23 towers that were found until 1999. Today the tower of Agia Triada (or tower in Chorio), at Terlaki and Rihti are preserved in good condition.