Santiago Cathedral of Bilbao was originally built during the 14th-15th centuries as Bilbao's main parish church, and was only declared cathedral in 1950 when the Roman Catholic Diocese of Bilbao was officially created. Its origins probably date to well before the foundation of the city in 1300, when Bilbao was little more than a small enclave of fishermen.
The church is consecrated in honor of the apostle Saint James the Great (Santiago), by virtue of being a point of transit for the pilgrims that followed the Northern branch of the Way of Saint James.
Architecturally, the present building is a mixture of styles: from the 15th century Gothic of the cloister and the main vault, where of special interest are the cloister and the beautiful portal that gives access Correo street (Puerta del Angel), to the ostentatious Gothic Revival façade and spire.
A curious custom is the addition of stone carvings of local merchants along the buttresses of the main vault.
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.