Apollonia was an ancient Greek city located on the right bank of the Vjosë river. Apollonia was founded in 588 BCE by Greek colonists from Corfu and Corinth, on a site where native Illyrian tribes lived, and was perhaps the most important of the several classical towns known as Apollonia.
Apollonia flourished under Roman rule and was noted by Cicero in his Philippicae as magna urbs et gravis, a great and important city. Christianity was established in the city at an early stage, and bishops from Apollonia were present during the First Council of Ephesus (431) and the Council of Chalcedon (451).
Its decline, however, began in the 3rd century AD, when an earthquake changed the path of the Aoös, causing the harbour to silt up and the inland area to become a malaria-ridden swamp. The city became increasingly uninhabitable as the inland swamp expanded, and the nearby settlement of Avlona (modern-day Vlorë) became dominant. By the end of antiquity, the city was largely depopulated, hosting only a small Christian community. This community (which probably is part of the site of the old city) built on a nearby hill the church of the Dormition of the Theotokos, part of the Ardenica Monastery.
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.