Hagia Sophia is one of the monumental structures of the Islamic and Christian beliefs, which has had the status of a church, a mosque, a museum and later a mosque until today. After the conquest of Istanbul in 1453, it was converted from a church into a mosque and in time it became the symbol of "chosen victory" for the Turkish-Islamic world and "chosen trauma" for the Christian-West world. In 1934, conversion from mosque to museum by the Decree of the Executive Deputies Delegation was seen as “chosen victory” for the withdrawal in terms of conservative-islamist-nationalist fractions in Turkey. With this study, the foreign policy dimension of converting Hagia Sophia, which has intense symbolic meanings, into a museum is discussed. The following theses are defended in the study: First, Turkish foreign policy makers has used Hagia Sophia as one of the psycho-political insrument of participating in the UK-led Western alliance system at a point where the international status quo began to crumble. Second, the compelling factor of transforming Hagia Sophia into a museum is Turkey's border security and political sovereignty that threatens the 1930s conjuncture.