Gytheio was the seaport of Ancient Sparta. It is the site of ancient Cranae, a tiny island where, according to the myth, Paris and Helen spent their first night together before departing for Troy.
In Roman times Gythium remained a major port and it prospered as a member of the Union. As purple dye was popular in Rome, Gythium exported that as well as porphyry and rose antique marble. Evidence of the ancient Gythium prosperity can be found by the fact that the Romans built an ancient theatre which is well preserved today and is still used occasionally. The ancient theatre and the city's Acropolis (west of the theatre) were discovered by the archeologist Dimitris Skias in 1891. Some time in the 4th century AD, the city was destroyed. What happened to Gythium is not recorded but it is thought to have been either sacked by Alaric and the Visigoths, pillaged by the Slavs or destroyed by the massive earthquake that struck the area in 375 AD.
After the earthquake Gythium was abandoned. It remained a small village throughout the Byzantine and Ottoman times. Its importance grew when Tzannetos Grigorakis built his tower at Cranae and more people came and settled at Gytheio. During the Greek War of Independence, refugees flooded into Mani and made Gytheio a major town.
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.