Another development is that visitors are not allowed to avail the services of a professional guide inside. Instead, visitors can scan a QR code and access an audio-visual tour. The guide audio tour comes in 23 different languages and provides information on 10 points of interest, out of which nine are in the upper gallery (most notably the "Heaven and Hell Gate", the 11th-century Viking Script graffiti, the mosaic of Constantine IX and Empress Zoe, and the Deësis mosaic depicting Jesus Christ, Virgin Mary and John the Baptist). The upper gallery is where tourists have access, whereas there's limited access on the ground floor.