Ein Hemed is a national park and nature reserve in the hills seven kilometres west of modern Jerusalem. A fortified Hospitaller building from the Crusader period, relatively well preserved, is arguably the main attraction beside the streams and lush vegetation.
The Kingdom of Jerusalem built fortresses along the road to Jerusalem in order to control the traffic to Jerusalem, and protect pilgrims visiting the Holy City. Farms were built using the spring water for irrigation.
Impressive ruins of a 30x40 metre Crusader courtyard building, whose southern wall survives to a height of 12 metres, are located on the north site of the riverbed. The building has several gates and two arched halls. Archaeological investigations indicate that it was built in 1140-1160, during the reign of Fulk of Jerusalem, in the same period as the fortresses on Tzova and Abu Ghosh. South of the building are a nature reserve and a Muslim cemetery.
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.