The Citadel of David is located near the Jaffa Gate on Jerusalem’s western wall.
The site, www.jewishvirtuallibrary.org has this helpful info:
The citadel of Jerusalem, known as the “Tower of David,” has been a landmark of the city since ancient times. . .Its location was chosen for topographic reasons – this is the highest point of the southwestern hill of Jerusalem, higher than any other point in the ancient city, including the Temple Mount. A series of fortifications built here in the course of more than twenty centuries, protected Jerusalem from the west and also overlooked and controlled the entire city.
A first archeological survey of the citadel, and excavations, were conducted between 1934 and 1947. Renewed excavations were undertaken after the reunification of the city, between the years 1968 and 1988, preparing the opening of the site to visitors.
Every period has left its mark and has been identified in the assemblage of architectural remains. In the citadel’s foundations are buried the remains of Jerusalem’s fortifications from the end of the monarchic period (8th to 6th centuries BCE) through the early Arab period (seventh to eleventh centuries). The outline of the citadel known today is from the Crusader period; the citadel itself was built in the mid-16th century by the Ottoman sultan Suleiman the Magnificent, and incorporates the remains of earlier citadels dating from Ayyubid and Mamluk times.
The Citadel is protected by a high wall and large towers, and it is surrounded by a wide, deep moat, part of which was blocked in modern times. The entrance is from the east, via an outer gate, a bridge over the moat and a fortified inner gate house.
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