Yazdegerd Castle is a ruined pre-medieval fortress traditionally dated to the Sassanid period, named after one of the Persian shahs Yazdegerd. Only fragments of walls and foundations remain, but the hilltop site gives a sense of how the original stronghold commanded the river valley below.
The castle is more an archaeological curiosity than a polished visitor site — there are no interpretive panels and access is informal. For visitors interested in Nakhchivan's pre-Islamic past it complements the medieval mausoleums in the city centre. Combine it with the Noah's Mausoleum, a short distance away in the same southern quarter.