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.

The Early Fortification
In the citadel’s courtyard, excavations have revealed the remains of fortifications dating from the late monarchic period to the Hellenistic and Roman periods. Here was the northwestern corner of the First Wall which is described in great detail by the contemporary Jewish historian Josephus Flavius. According to him, the First Wall extended from here towards the Temple Mount to the east and also to the south, surrounding Mount Zion and then joining the southern wall of the City of David. (War V,4,2) Remains of this wall and of three large towers are preserved to an impressive height of over 7 m. in the citadel courtyard. Several construction phases belonging to different periods can be observed, distinguishable by differences in the masonry and in the method of laying the stones.

The Monarchic Period
The wall was first built in this area by Hezekiah, king of Judah, at the end of the 8th century BCE. A detailed description of its construction on the eve of the Assyrian invasion of Judah, is in the Bible: He [Hezekiah] set to work resolutely and built up all the wall that was broken down and raised towers upon it, and outside it he built another wall. (2 Chron. 32:5) The remains of that incredibly wide wall (ca. 7 m.!), built of large boulders, were uncovered at great depth on the bedrock of the hill. This mighty fortification protected a new residential quarter built on the southwestern hill of Jerusalem which, until that time, comprised only the City of David and the Temple on Mt. Moriah. The wall was damaged in 587/6 BCE, when Jerusalem was conquered by the Babylonians.

The Second Temple Period

After some 300 years, the First Wall was restored by the Hasmonean rulers, who invested considerable effort in increasing the area of Jerusalem and strengthening its fortifications. At the Citadel, a 4 m. thick wall with two mighty towers, dating from this period, was uncovered. It was constructed in two phases: in the first, rectangular ashlars were laid in header fashion, a Hellenistic building style; in the second phase, ashlars with dressed margins and protruding central boss on the outer faces, were laid in alternating courses of headers and stretchers.

At the end of the 1st century BCE, King Herod improved the fortifications in this area and added three huge towers to the First Wall. A precise description, including the measurements of these towers is found in the writings of Josephus Flavius. The towers, which rose high over the city, were named Phasael (after Herod’s brother), Hippicus (after Herod’s friend) and Mariamne (after Herod’s Hasmonean wife). They were built to protect the large royal palace south of them, which apparently included the area of the present day citadel and part of the Armenian Quarter. Remains of the podium built inside the First Wall to support the palace were found during excavation of the Citadel. It consists of a grid of retaining walls which held earth fill, thus artificially raising the ground level by some 5 m.

One of the towers built by Herod has survived to the present day. This is the so-called Tower of David which is incorporated into the fortifications of the eastern side of the present Citadel. It should be noted that the traditional name Tower of David, said to be the result of the incorrect identification of this structure by Christian pilgrims in the Byzantine period, has in fact much earlier origins: Josephus refers to the southwestern hill of Jerusalem of that period as the "Citadel of King David." (War V,3,1)

The dimensions of the Tower of David are approximately 22 x 18 m., consisting of 16 courses of large ashlar stones weighing over a ton each. They have trimmed margins and a flat central boss, carefully laid without gaps, and the interior of the tower is filled with large ashlars. The Tower of David is one of the most impressive examples of royal construction of the Second Temple period in Jerusalem. It stands to this day to a height of 20 m.!

The three towers built by Herod and the other fortifications created a powerful, well protected fortress. Thence the decisive strategic role it played in the First Jewish Rebellion against Rome (66-70 CE) which ended with the siege of the city, its conquest and destruction. This is attested to in another tower, located in the southern part of the citadel, which was built in the 1st century CE and was destroyed during the rebellion: a thick layer of debris, including stones, plaster, and charred wooden roofing beams, was uncovered.

The Roman Period

After the destruction of Jerusalem in 70 CE, the Romans established a camp to quarter the Tenth Legion on the southwestern hill of the city. It was protected by the three towers built by Herod, which the Roman commander Titus had ordered to be left intact. (Josephus, War VII,1,1) Remains of this Roman Legion camp were uncovered in the courtyard of the Citadel; they include clay water pipe sections bearing seal impressions reading "L·X·F," for Legio X Fretensis, the full name of the Tenth Legion.

The Byzantine Period

During the Byzantine period, the fortifications of the citadel, including the Tower of David, were restored. Nearby, monks built monasteries and other religious institutions, as reported by several contemporary Christian travelers. Only fragmentary remains of fortifications, walls, cisterns and a lintel engraved with a cross, date to this period.

The Early Arab Period

In the 8th century, during the period of Arab rule over Jerusalem, a new citadel was established. Among its remains are a rounded corner tower measuring 10 m. in diameter, from which 4-m. thick walls extend to the north and to the west. The precise plan of this citadel is not known, as severe damage was caused when the Crusaders built their citadel.

The Crusader Period

The Crusader citadel, built in the 12th century, was innovative and extended northward and westward, beyond the ancient city wall. The early city wall became an inner terrace wall in the courtyard, which was buried under some 10 m. of debris, protecting and preserving it until its exposure during the archeological excavations.

Today, for the first time in its long history, the citadel is no longer used for military purposes. Instead, it functions as the museum of the history of Jerusalem. Presented in its various towers are exhibits tracing 5,000 years of the city’s history. In the courtyard, remains of the First Wall and its towers, of the Second Temple period and of the fortification from the Byzantine and early Arab periods, have been preserved and serve as a veritable guidebook to the long history of Jerusalem’s fortifications on the southwestern hill.