Palmyra Castle — also known as Fakhr-al-Din Castle — sits on a hilltop about a kilometre from the ancient ruins, commanding a panoramic view over the entire site and the desert that surrounds it. It is a medieval Arab fortification, not a Roman one, built in the 15th century by the Mamluk sultan Qaitbay and later expanded by the Druze prince Fakhr-al-Din al-Ma'ani II.
The castle was used as a military base during various phases of the Syrian conflict and suffered some damage, but the main structure survived. The view from the top — ancient columns scattered across the desert below, the oasis palms of modern Tadmur to one side, the vast emptiness of the Syrian Desert in every other direction — was one of the most extraordinary in the Middle East. Whether it is accessible now is unknown.