The Cathedral of St. Mary the Great is a catholic church and fortress built in the fifteenth century, which preserves a Romanesque appearance.
Its facade is flanked by two large towers topped by battlements and highlights its beautiful Gothic portal with archivolts with sculpted scenes from the Passion of Christ and sculptures of the Apostles. It is a Romanesque church with a Latin cross and inside is separated by three arches supported on pillars ships. It is classified as Imóvel of Public Interesse.
Inside, are the chapels of St. Bernard (by Fernão Brandão) and the chapel of the Blessed Sacrament, attributed to stonemason, João Lopes the 'old'.
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.