The remains of the Red Mosque are visible to the south of the upper fortress, near the west surrounding-wall of the castle. It is believed that this monument is the mosque that Elvia Celebiu identifies as Sultan Bajaziti’s mosque when he was writing about the castle. The building contains the hall for prayers with an almost square-shaped floor plan and forms a vestibule in front of it with the same width. On the left side of the hall is the minaret. This placing, different from other mosques, seems to be due to the close proximity of the boundary wall to the southwest. The shrine’s walls, as well as the foundation of the minaret, were built using the of horizontal bricks and one or two vertical bricks between the calcareous stones. The date of the mosque is uncertain, however, based on Celebiu’s data, the technique used and its position, the likely conclusion is that the mosque is from the 15th century CE. Whether Sultan Bajaziti built it, or if it is an earlier construction, makes it even harder to give a precise date. The Turkish garrison was stationed here between the second half and the end of the 15th century CE.