The Monastery of San Filippo Fragala, located in the small town of Frazzanò, is one of the oldest basilian monasteries in Sicily. Approximately 2km from the town centre, the monastery was built from the Count Ruggero and his wife Adelasia in 1090 and was an important centre for religious studies on saints. In 1866 the rich library of the monastery was transferred into the town to create an easier access to the books but unfortunately they were not well kept from the authorities and most of it got dispersed. Lucky the greek and latin papers that dated prior to the 18th century were transferred to the museum of Palermo where they were taken better care of.
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.