Craignethan Castle is a ruined castle in South Lanarkshire, Scotland. Built in the first half of the 16th century, Craignethan is recognised as an excellent early example of a sophisticated artillery fortification, although its defences were never fully tested.
Craignethan is built on an imposing site above a bend in the River Nethan. Steep slopes protect the castle on the south, north and east sides, but the castle is actually overlooked by higher ground to the west, making it far more vulnerable than it appears. Craignethan's defences are therefore concentrated towards the west. The castle comprises a low central keep, within a rectangular walled courtyard. To the west is a deep ditch and beyond, a larger outer courtyard. The rectangular keep measures 21m by 16m, and was originally of two storeys plus an attic.
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.