The castle sits atop a 650-metre-high (2,130 ft) hill east of Tartus, Syria, in the Homs Gap. On the other side of the gap, 27 kilometres (17 mi) away, was the 12th-century Gibelacar Castle (Hisn Ibn Akkar).

The castle was strategically located at the southern edge of the Jibal al-Alawiyin mountain range and dominated the road between Homs and Tripoli. Krak can be classified both as a spur castle and a fully developed concentric castle.

circa 1200 CE

The site was first inhabited in the 11th century by Kurdish troops garrisoned there by the Mirdasids. According to the 13th-century Arab historian Ibn Shaddad, in 1031, the Mirdasid emir of Aleppo and Homs, Shibl ad-Dawla Nasr, established a settlement of Kurdish tribesmen at the site of the castle, which was then known as "Ḥiṣn al-Safḥ". The early castle was substantially different from the extant remains and no trace of this first castle survives at the site.

In 1142 it was given by Raymond II, Count of Tripoli, to the order of the Knights Hospitaller. The Hospitallers began rebuilding the castle in the 1140s and were finished by 1170 when an earthquake damaged the castle.

In 1271 Mamluk Sultan Baibars captured Krak des Chevaliers after a siege lasting 36 days, supposedly by way of a forged letter purportedly from the Hospitallers' Grand Master that caused the Knights to surrender.

During the Ottoman period (1516–1918), the Crac housed a company of müstahfızan (equivalent to local janissaries), and was commanded by a dizdar (castle warden).

In the late 19th or early 20th century a settlement had been created within the castle, causing damage to its fabric. The 500 inhabitants were moved in 1933 and the castle was given over to the French Alawite State, which carried out a program of clearing and restoration. When Syria declared independence in 1946, it assumed control.

circa 1200 CE

The Outer Ward
The outer ward of the Krak des Chevaliers (identify) of the Crac, was constructed in the 13th century CE and followed the lay of the land. It added further fortification advantages to the upper or the inner bailey. The outer ward complex comprised of fortification towers connected with curtain walls, and inside the walls were the zwinger areas on the , and moat. The peasants who took refuge inside the castle during sieges, were also kept in this section.

To the south of the outer ward was a triangular outwork and the Crusaders may have intended to build stone walls and towers around it.

circa 1200 CE

The Inner Ward
The inner ward of the Krak des Chevaliers or the inner bailey (identify), although reconstructed, renovated and added on several times over the years, it premarily dates back to the earliest phases of Crusader construction of the castle, constructed majorly between 1142 and 1170 CE.

Between 1142 and 1170, the Knights Hospitaller initiated an extensive construction program at the site of Krak des Chevaliers. This phase of development introduced a stone curtain wall reinforced with square towers that slightly projected outward, enhancing the defensive capability. The primary entrance was strategically positioned between two towers on the eastern side, while a postern gate was located within the northwest tower. At the heart of the castle lay a courtyard encircled by vaulted chambers, which functioned as essential operational and defensive spaces. The castle’s irregular layout conformed to the natural contours of the terrain, a characteristic feature of Crusader fortifications. Steep slopes offered inherent defensive advantages on most sides, leaving only one side vulnerable, where defences were heavily concentrated. The structural elements from this period were later integrated into subsequent construction phases.

Significant modifications occurred in the 13th century when the castle was extensively remodelled. New defensive walls were erected around the inner court, closely following the earlier fortifications. On the western and southern sides, a narrow gap between these walls was converted into a defensive gallery, allowing defenders to launch projectiles at attackers. The additional protection of a steeply sloping glacis reinforced these walls, providing resilience against siege equipment and seismic activity. Four prominent round towers, rising vertically from the glacis, served dual purposes: military defence and accommodation for the garrison, which peaked at approximately 60 knights. The southwest tower was specially designed to house the chambers of the Grand Master of the Knights Hospitaller. Unlike other sections, the southern face lacked machicolations, and the area between the inner and outer walls, particularly in the eastern section, featured an open cistern. This cistern, fed by an aqueduct, functioned as both a water reservoir and a defensive moat.

Within the northern section of the small courtyard stood a chapel, while the southern section featured an elevated esplanade. This esplanade, raised above the rest of the courtyard, likely housed storage spaces and provided shelter, doubling as stables and a defensive feature against projectiles. The western side of the courtyard was lined by the Knights’ Hall, originally constructed in the 12th century but extensively refurbished during the 13th-century renovations. The interior, characterized by intricate tracery and refined Gothic architectural elements, represents the height of sophistication in Crusader architecture and is believed to date from the 1230s.

These successive architectural developments underscore the strategic and functional sophistication of Krak des Chevaliers as one of the most formidable Crusader castles of its time.