The edifice also has a richly gilded prayer niche or mihrab. The mihrab is a masterpiece of architectural art, with geometric and flowing designs of plants. Other prominent features were an open court (sahn) surrounded by arcades, screens of wood, minarets, colourful mosaics, and windows of coloured glass. The walls of the mosque had Quranic inscriptions written on them. As many adherents of Islam reject sculptural or pictorial representations of people or of God within religious contexts, all decoration of the cathedral is accomplished through tile work, calligraphy and architectural forms. Arrazi, an Arab writer, speaks of the valuable wine-coloured marble, obtained from the mountains of the district, which was much used in embellishing the naves of the mosque.