Biniac has two circular burial navetas that were used around 1400 B.C. and are from an earlier period than the long rectangular constructions like the Es Tudons and Rafal Rubí navetas. The east naveta was built on bedrock and has only one oval-shaped chamber, accessed via a perforated stone slab. Several slabs that had fallen over were found inside. The west naveta is also oval-shaped and the wall on the south side has dry stone cladding, clearly added at a later date.
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.