Montségur is often named as a candidate for the Holy Grail castle - and indeed there are linguistic similarities in the Grail romance Parzival (circa 1200-1210) written by Wolfram von Eschenbach. In Parzival the grail castle is called Monsalvat, similar to Montségur and meaning the same thing: "safe mountain, secure mountain." The name of Raymond de Péreille, the actual historic seigneur of Montségur has slight simularities to protagonist of Eschenbach's epic, the knight Parzival. In Jüngerer Titurel (1272) by Albrecht von Scharfenberg, another Grail epic, the first king of the Holy Grail is named Perilla.

Unfortunately for many romantics, the present fortress ruin at Montségur, is not from the Cathar era. The original Cathar fortress of Montségur was entirely pulled down by the victorious French Royal forces after its capture in 1244. It was gradually rebuilt and upgraded over the next three centuries by Royal forces. The current ruin so dramatically occupying the site, and featured in illustrations, is referred to by French archeologists as "Montsegur III" and is typical of post-medieval Royal French defensive architecture of the 1600s. It is not "Montsegur II", the structure in which the Cathars lived and were besieged and of which no trace remains today.