A hundred years ago, underground the Istanbul, there were only historical remains and dead people. However, according to municipality record, today, in 2024, at any moment of the day, 200,000 people moving underground transportations in Istanbul. The population of 200,000 means a medium-sized city so it can be declared that there is a city beneath Istanbul. And along with the development of transportation this population is gradually increased every day. The medium-sized city normally needs a mosque to pray so that underground population of Istanbul has the same need also. However, there is no convenient place to meet the need of worship of this population. Today, the small room-sized areas are used as a prayer places, and sometimes even those are not available. Therefore, in the subterranean of Istanbul, building a mosque is necessary issue. Building a mosque underground of Istanbul can be examined under two points. One of them is transportation network that has a determinant point to place potential future mosque. The other one is considering historical heritage that includes both above and below of Istanbul’s ground. While the underground of Istanbul has a heritage traced back to Byzantine times, on surface, the ground of Istanbul has a historical mosque silhouette. Both of these treasures are determinant points to build the potential future mosque in subterranean of Istanbul. In this article, considering Istanbul's both underground treasure, dating back to the Byzantine period, and ground silhouette treasure and underground transportation network, potential future mosques will be addressed.

In recent years, policy is the one of the paradigm is shaping Istanbul’s mosque style especially in Taksim Mosque. The Taksim Mosque has been a topic of discussion in politics for 70 years. During its 70-year history, the mosque's fate has been influenced by the changing policies of ruling parties, resulting in periods of attention and neglect. Eventually, in 2021, the Taksim Mosque was build in a fusion of Ottoman and Seljuk architecture style that is affected by the Neo-Ottomanism policy adopted by the AKP, ruling government. We encounter three proposals for the Taksim Mosque project. The first one was the "Taksim Republic Mosque and Museum of Religions" project, commissioned in 2012 by the Taksim Mosque Culture and Art Foundation to the architect Prof. Dr. Ahmet Vefik Alp. In this project, architect Alp embraced the approach of designing the mosque, to be built in Taksim Square – a symbol of our Republic and modern Turkey – with a contemporary and creative architectural interpretation, under the condition of preserving its symbolic values. Another contemporary project for the Taksim Mosque was designed by Hassa Architecture, Hilmi Şenalp. He proposed a mosque for the Taksim project with a modern abstract mosque style. However, in line with Neo-Ottomanism, ruling government favored a more traditional approach to the mosque's design that is the third proposal created by Şefik Birkiye. This project has classical architectural elements that reflected the heritage and historical aesthetic of the Ottoman era. Not only because of Neo-Ottomanism policy but also the political significance of Taksim Square affects perceiving Taksim Mosque as a political element. Taksim Square, where the mosque is located, has also served as a reflection of various political ideologies. Turkification policies adopted by early years of the Republic and the policy of modern states impact to Taksim Square. Therefore Taksim mosque because of the building in Taksim Square serves as a political tool also. This article demonstrates that under these two factors: Neo-Ottomanism policy and political significance of Taksim Square, Taksim mosque is notable example effecting by the political paradigm.