The Golden Gate, as it is called in Christian literature, is the only eastern gate of the Temple Mount and one of only two that used to offer access into the city from that side. It has been walled up since medieval times. The date of its construction is disputed and no archaeological work is allowed at the gatehouse, but opinions are shared between a late Byzantine and an early Umayyad date.
The Hebrew name of the Golden Gate is Sha'ar HaRachamim (שער הרחמים), Gate of Mercy. In Jewish sources the eastern gate of the Temple compound is called the Shushan Gate. If the Golden Gate does preserve the location of the Shushan Gate, which is only a presumption with no archaeological proof, this would make it the oldest of the current gates in Jerusalem's Old City Walls. According to Jewish tradition, the Shekhinah used to appear through the eastern Gate, and will appear again when the Anointed One (Messiah) comes and a new gate replaces the present one; that might be why Jews used to pray in medieval times for mercy at the former gate at this location, another possible reason being that in the Crusader period, when this habit was first documented, they were not allowed into the city where the Western Wall is located. Hence the name 'Gate of Mercy'.
In Christian apocryphal texts, the gate was the scene of the meeting between the parents of Mary after the Annunciation, so that the gate became the symbol of the virgin birth of Jesus and Joachim and Anne Meeting at the Golden Gate became a standard subject in cycles depicting the Life of the Virgin. It is also said that Jesus passed through this gate on Palm Sunday, giving it also a Christian messianic importance beside the Jewish one.
In Arabic, it is known as Bab al-Dhahabi, also written Bab al-Zahabi, meaning 'Golden Gate'; another Arabic name is the Gate of Eternal Life.
The present gate was probably built in the 520s AD, as part of Justinian I's building program in Jerusalem, on top of the ruins of the earlier gate in the wall. An alternate theory holds that it was built in the later part of the 7th century by Byzantine artisans employed by the Umayyad khalifs.The Ottoman Turks transformed the walled-up gate into a watchtower. On the ground floor level a vaulted hall is divided by four columns into two aisles, which lead to the Door of Mercy, Bab al-Rahma, and the Door of Repentance, Bab al-Taubah; an upper floor room has the two roof domes as its ceiling.
Closed by the Muslims in 810, reopened in 1102 by the Crusaders, it was walled up by Saladin after regaining Jerusalem in 1187. Ottoman Sultan Suleiman the Magnificent rebuilt it together with the city walls, but walled it up in 1541, and it stayed that way until today.
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.