The Catacombs of Marcellinus and Peter are ancient catacombs situated near the church of Santi Marcellino e Pietro ad Duas Lauros. Their name refers to the Christian martyrs Marcellinus and Peter who, according to tradition, were buried here, near the body of St. Tiburtius. In 2006, over a thousand skeletons were discovered in these catacombs; the skeletons were stacked one on top of each other and still bore the togas they were buried with.
The Catacombs are open only on Saturdays and on Sundays for individual visitors.
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.