Hagia Sophia (from Greek- “Holy wisdom”) is one of the most significant monuments in the world and the most spectacular Byzantine construction ever built. It initially executed the purpose of the main cathedral of Constantinople, but during the centuries it has served as a mosque under the Ottoman empire, and nowadays it has been turned into a museum of both Christian and Muslim art. The cathedral is built on the foundations of 2 previous Byzantine Christian churches, as well as a pagan temple. This is the place where Byzantine rulers were crowned and was the biggest operational cathedral in the ancient capital city throughout the Byzantine period and the Ecumenical Patriarchate of Constantinople for a millenium. The building itself is quite spectacular in the way it was made ( it combines the features of both a basilica and a centralized building in an organized manner)- it contains 2 floors, which are centred on a big nave that has a giant 32- metre main dome, supported by pendentives,2 other semi- domes, and giant marble piers. The spectacular “museum” also contains numerous galleries and 3 aisles, and it is dedicated to Logos- the second person of the Holy Trinity. The nowadays museum/mosque is situated where the ancient city of Constantinople previously stood- in Istanbul, overlooking the Bosphorus strait and the Sea of Marmara. The monument was constructed under the direction of the Byzantine emperor Justinian I, who hired two great mathematicians and mechanicians to carry out the grand cathedral’s design and plan- Anthemius and Isidorus. The Byzantine architectural masterpiece was built in the 6th century CE- from 532 CE to 537 CE, surprisingly for 6 years only, after the Nika riots took place in and were therefore silenced in 532 AD by Justinian. There are numerous reasons behind the building of this historical monument- for one the Nika riots gave Justinian I the opportunity to envision a splendid replacement of the destroyed in the fights previous church. In this way Justinian not only showed his authority and true power to the people ruled by him, but also his and the empire’s connection with Christianity and the Eastern Roman church as a whole. The monument also immortalized the power of Christianity over the other pagan practises and would later become the symbol of power of another dominating world religion- Islam.The UNESCO should consider strongly the idea of giving protection to this marvelous piece of architecture, in which melt the art styles and histories of both great empires and dominant world religions in peace.This monument is also important simply because it has influenced the development and evolution of European, Muslim and Christian art and architecture, which gives it a very important place in the human history. There are several reasons behind the need for this monument to be under the protection of UNESCO. Firstly, the mix of architectural styles makes the cathedral truly “stick out” as a very important cultural landmark. An example to this may not only be the support to the church’s massive dome- the pendentives, the intricate and colorful Byzantine mosaics , but also the minbars and the wooden minaret- which show the evident change in the cathedral’s purpose during the Ottoman empire times, but simultaneously gave it a charm like no other historical building in the world possesses- the mix between predominate Byzantium and a sprinkle of Ottoman style. Secondly, Hagia Sophia is one of the few monuments that on a grand scale influenced the architecture and art style of a big majority of constructions- from military to religious. For instance, the terrestrial line built by Theodosius II with its second line of defence was the leading reference for military architecture in Europe, while the cathedral also gave the standard for domes in mosque architecture- as in the progress “…Muslim architects developed enormous and varied types of domes…” (http://iieng.org/images/proceedings_pdf/E0516006.pdf) – some examples for influenced by the Byzantine Hagia Sophia mosques include the Dome of the Rock and the Umayyad Masjid. Finally, Hagia Sophia should be protected by UNESCO because of its historical significance and uniqueness- as it has been one of the main Christian cathedrals and the Imperial Mosque during Ottoman and Byzantine rule. Nowadays, this precious building is a museum, exposing the public to the beauty of the Middle Ages and Antiquity. In conclusion, I believe that the Hagia Sophia museum should be under UNESCO protection because of several factors- the monument is one of its kind in the world, its architectural and art styles are historically important and very unique , as well as the sole fact that the monument is the symbol of the unity between the two dominant world religions and it represents the beauty through the variety.