The Tomb of Leonidas has an impressive edifice (12.5m × 8.30 m), probably dating back to the late 5th century BCE. It was made of massive limestone and its interior was divided in two connected chambers. The eastern chamber was 3.15 meters long, had the form of a pronaos (vestibule) and was ornate with columns. Until today, the use of the edifice has not been verified.It is believed to be a cenotaph, while many researchers share the opinion that it is the temple of Karneios Apollo.
Although there is no indication on the correlation between the temple and the legendary king of Sparta, according to local tradition and the travel writer Pausanias, the remains of Leonidas were transferred and buried there. It is because of this, that the locals believe it to be the tomb of Leonidas. Pausanias also mentions that annual games were hosted here to honor the memory of the Spartan king.
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.