In 527 there was a mighty ruler in Constantinople – Emperor Justinian. He wanted to bring back the brilliance of Roman Empire. So he ordered all Roman laws to be gathered in one compilation. This is the famous Justinian Code. Even nowadays everyone, who is willing to be a lawyer or a judge, is obliged to read it. In the same way, in which the Romans preserved the treasures, left by the Hellenes, Justinian preserved the creations of the Romans. This ruler left us one precious treasure – The church of Hagia Sophia in Istanbul, one of the most beautiful, magnificent and unique buildings, ever created by human genius. It marked the beginning of a new type of religious buildings, the so called dome churches. So the period of the High Middle Ages started. The Byzantine architects further improved the inherited tradition from the Romans to cover their churches by large semi spherical domes, which resembled the heaven’s vault, while inside they decorated the churches with fine painting, made of multitude of small stones of different colours. These were the unique Byzantine mosaics.