The Panathenaic Stadium or Kallimarmaro is a multi-purpose stadium in Athens. One of the main historic attractions of Athens, it is the only stadium in the world built entirely of marble.
A stadium was built on the site of a simple racecourse by the Athenian statesman Lykourgos c. 330 BC, primarily for the Panathenaic Games. It was rebuilt in marble by Herodes Atticus, an Athenian Roman senator, by 144 AD and had a capacity of 50,000 seats. After the rise of Christianity in the 4th century it was largely abandoned.
The stadium was excavated in 1869 and hosted the Zappas Olympics in 1870 and 1875. After being refurbished, it hosted the opening and closing ceremonies of the first modern Olympics in 1896 and was the venue for 4 of the 9 contested sports. It was used for various purposes in the 20th century and was once again used as an Olympic venue in 2004. It is the finishing point for the annual Athens Classic Marathon. It is also the last venue in Greece from where the Olympic flame handover ceremony to the host nation takes place.
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.