Ibn Maan Citedel (Fakhr al-Din al-Maani citadel):

2 km north of the main ruins of Palmyra; while the castle itself is rather poorly constructed, it is well preserved and a visit is an essential adjunct to any exploration of Palmyra. The splendor of the scene either at sunset or at dawn as the sun rises over the ruins and the mountains behind is a memorable souvenir of Palmyra.

The castle has for long been attributed to the Lebanese Maanite Emir, Fakhr al-Din (1590 - 1635), who tested the limits of Ottoman flexibility in the early 17th century by expanding his area of direct control well beyond Mount Lebanon as far east as the Syrian desert, hoping to present the Ottomans with a fait accompli that they would be too weak-willed to reserve. He was wrong. Recent Polish research has confirmed that Fakhr al-Din made use of and earlier Arab castle on this site, a late Ayyubid construction of around 1230 (contemporary with the constructions of Bel Temple at Palmyra).

It's based on a triangular fortress of seven towers, extended later in the 13th century with second curtain walls to the east and west, the whole ringed by a deep ditch. There are memorable views for 360º around but perhaps the most striking is the view to the north along the spine of the Jebel al-Tadmoria as the rising sun begins to color its rugged slopes.