With its impenetrable walls, winding corridors, and massive towers, Crak des Chevaliers is a spectacular rxample of medieval architecture.
The Hospitallers rebuilt Krak and expanded it into the largest Crusader fortress in the Holy Land, adding an outer wall three meters thick with seven guard towers eight to ten meters thick to create a concentric castle.
The fortress may have held about 50–60 Hospitaller knights and up to 2,000 other foot soldiers; the Grand Master of the Hospitallers lived in one of the towers.
Visitors first encounter massive curtain walls encircling the fortress. These walls are punctuated at roughly 150-foot intervals by round towers. Narrow arrow loops perforate each tower, providing a tactical vantage for archers hidden inside. The most vulnerable stretch of wall is along the south end, which is thus the most heavily fortified, To protect this critical area, the Hospitallers dug a ditch and installed the largest defensive wall anywhere in the castle, nearly 100 feet thick.
The buildings in the inner ward were rebuilt by the Hospitallers in a Gothic style. These buildings included a meeting hall, a chapel, a 120-meter-long storage facility, and two vaulted stone stables which could have held up to a thousand horses. Other storage facilities were dug into the cliff below the fortress.
Krak can be classified both as a spur castle and a fully developed concentric castle. it is estimated that the Hospitallers could have withstood a siege for five years.
The southern side of the castle is the most vulnerable to attack, as this is where the spur on which the castle stands is connected to the next hill, so that siege engines can approach on level ground. The inner defences are strongest at this point, with a cluster of towers connected by a thick wall. The inner curtain wall is up to 100 feet thick at the base on the south side, with seven guard towers 30 feet in diameter.
Between the inner and outer walls at the southern side there is a large open cistern, fed by an aqueduct from outside the castle. The square tower in the South does not date from the crusader period, but was added when the Mamluks repaired the damage from their successful siege after they had taken over the castle.
The most elegant feature is the thirteenth century Gothic colonnade, or loggia, with beautiful peaked vaultsdesigned as an entrance to the great hall. The delicate arches The loggia, along with the chapel, is a visible reminder that Krak was a religious monastery just as much as a military stronghold.. A surviving Latin inscription on one of the lintels reads: "Grace, wisdom and beauty you may enjoy, but beware pride, which alone can tarnish all the rest."
On the eastern side between the inner and outer walls a vaulted ramp leads from the outer to the inner gate. The ramp makes a number of elbow turns and is defended by arrow slits and machicolations, making it a strongly defended bent entrance. On the northern side, there is a postern gate flanked by two towers. On the Western side, the ward between the outer and inner walls does not contain any buildings, but it is here that the concentric principle of defence is most evident, with the inner defences completely dominating the outer wall. The walls on all sides contain passages that act as shooting galleries or vaults leading to arrow slits.