The Medieval Castle of Tilos is located to the north of Megalo Chorio, the capital village of the island. Built atop a hill by the Knights of Saint John, during the late Byzantine period, this medieval castle offers spectacular views across the bay of Agios Antonios and a late-afternoon visit probably offers one of the best sunsets on the island. The church of Archangel Michael was built within the castle complex in the post-Byzantine period.
An entire village was once built within the castle walls to protect from the pirates who plundered the Aegean in the Middle Ages and it was not until the 18th century, when piracy was suppressed, that many of the inhabitants started to migrate down and settle closer to the foothill.
The castle and the church enclosed within the walls were built over the remains of a Hellenistic acropolis which included a temple dedicated to Apollo and Athena. The imposing castle had a triangular ground plan, but nothing much remains of it except for the external wall, some ancient and medieval ruins, cisterns and the ruins of the church along with some of its 14th-15th-century frescoes. To the east of the Castle, you can find the ruins of the Messaria fortress, built around 1366 by the Knights of Saint John.
The fortress protected the road leading towards the fertile plains of the island. Within its massive walls, the ruins of several buildings and of a little church are found. The remains of a Byzantine settlement and of small chapels dating back to the 13th century can be found close to the fortress. The walls of the churches are covered with frescoes. Above this fortress, there lies the famous Charkadio Cave, where the fossils of a pygmy elephant were unearthed in 1971.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.