Northburgh Castle, also known as Green Castle or Greencastle Castle, is a 13th/14th-century ruin in Greencastle, Ireland. Completed in 1305 by Richard Óg de Burgh, it controlled Lough Foyle and served expansion plans. Edward Bruce captured it in 1316, and it later became an O'Doherty stronghold. The castle features an oval enclosure with a twin-towered gatehouse and a later large tower. Influenced by Edward I, it symbolized a shift from pure military structures to administrative centers. Damaged by cannon fire, the castle is now managed by the Irish government and accessible from the town and shore.
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.