Sanctuary de Sant Salvador, an old hermitage, 509m above sea level at the highest point of the Serra de Llevant was the senior house of Mallorca's monastic order and the last to lose its monks in 1992.
The walls were built in the 14th century to protect the town from pirates or invaders. There are walkways and a simple cafeteria along the walls, and a neoclassical church, which was built in 1832.
It is still a popular place of pilgrimage, flanked by two enormous landmarks - to one side a 14m stone cross, to the other a 35m column topped by a statue of Christ holding out his right hand in blessing. The views from the terrace take in Cabrera, Cap de Formentor and several other hilltop sanctuaries dotted across the plain. From the statue of Christ you look out towards the Castell de Santueri, a 14th century rock castle built into the cliffs on the site of a ruined Arab fortress.
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.