It guarded the route between Latakia and the city of Antioch. The castle, situated approximately 25 kilometers (16 miles) northeast of Latakia, occupies a prominent location near the town of al-Haffah. Historically, the site has borne several names, reflecting the diverse cultures that have influenced the region. Its traditional Arabic name, Ṣahyūn, is etymologically linked to the term "Zion". According to historian Hugh N. Kennedy, this name has been supplanted in modern times (around 1950 CE) by the title Qalʿat Ṣalāḥ al-Dīn, or "Saladin's Castle", to align with contemporary sensitivities regarding its nomenclature.

The Byzantines, who once held sway over the region, referred to the site as Sigon, a name later adapted by the Frankish Crusaders, who called it Saône. Each of these names underscores the castle's historical significance as a cultural and military stronghold that bridged Byzantine, Islamic, and Crusader domains. Its strategic placement and historical resonance make it an enduring symbol of the complex interplay of civilizations in the medieval Levant.

circa CE

The Byzantine Emperor John I Tzimiskes was the first to captured the site in 975 CE and after that the fortress remained under Byzantine control until around 1108 CE.

In the early 12th century CE the Franks took control of the site and it became part of the newly formed Crusader state of the Principality of Antioch. The Crusaders undertook an extensive building and expansion program, giving the castle most of its current plan and architectural appearance.

In 1188 CE the Sahyun Castle fell to the forces of Saladin after a three-day siege. Salahdin after taking the caslte, rebuilt and re-fortified parts of outer ramparts. Subsequently, at sometime during the reign of Salahdin, the fortress was give to a local emir, Nasr al-Din Manguwiris (also known as Mankurus ibn Khumartigin), loyal to the Ayyubids. In 1272 CE Nasr al-Din ceded the castle to the Mamluk Sultan Baibars. Around the same time a small town established adjacent to Sahyun Castle, as noted by the emir of Hama, Abu'l-Fida (reigned 1273–1331 CE).

From 1280 CE till 1287 the castle was held by Sonqor al-Ashqar, local governor of Damascus. During this period, under Sonqor, the castle became the administrative center of a small semi-independent emirate comprising of immediate surrounding region. However, in 1287 CE it was taken by the Mamluk Sultan al-Mansur Qalawun when Mankurus unable to hold the defense, surrendered.

Under the Mamluks, the region of Sayhun Castle was made part of the province of Tripoli and remaind a significant stronghold and prospered. The castle is known to have remained significant and prosperous under the Mamluks until at least the late 14th century CE. In later decades of the 14th century CE, however, Sahyun was abandoned, for uknown reasons.

Sayhun again saw activity after the Ottoman conquest of Syria, Sahyun Castle became an Ottoman fortress.

circa CE

Sahyun fortress was built on a ridge some 700 metres (2,300 feet) long between two deep gorges. The Sahyun Castle or Salahdin Caslte features a barred-spur layout, which means part of the plateau was isolated from the rest of the mountain top by a ditch. This ditch also acted as a quary for the building material used in constructing the eastern walls above the eastern side of the fortress ridge. The spur on which the castle is built was connected to a plateau in the east via a drawbridge. The Byzantines added a wall across the east side of the ridge to enhance the defences sometime during the tenth of eleventh centuries CE. These walls created an irregular enclosure and were studded with flanking towers. Adjacent to the fortification, at the eastern end of the ridge was a settlement. One of the most magnificent features of the fortress is the 28 meter deep ditch (inspect), which was cut into living rock (rock that is not detached but still forms part of the earth). The creation of the ditch has been attributed to the Byzantines. This ditch, which runs 156 meters along the east side, is 14 to 20 meters wide and has a lonely 28 meters high needle (inspect) to support the drawbridge.

The modern day entrance to the castle is through an entrance on the south side of the fortress. On the right of the entrance is a tower, a bastion built by the Crusaders. There is another a few meters further. There is a cistern for water storage and some stables just next to a massive keep that overlooks the ditch. This keep has walls of 5 m thick and it covers an area of nearly 24 m2. Further on to the north is the gate where the drawbridge used to be. Also evident are the Byzantine citadel, located at the center of the fortress, another large cistern, the Crusader tea house, and a Crusader church adjoining one of two Byzantine chapels. As for the Arab additions to the fortress, they include a mosque, which dates back to Qalawun's reign, and a palace, which includes baths with courtyards and iwans. This has been slightly restored.