What is the Main Mosque in Istanbul?

The main mosque in Istanbul is the Sultan Ahmed Mosque, also known as the Blue Mosque. It is one of Istanbul's most famous landmarks and a major tourist attraction. 

The mosque was built in the early 17th century during the reign of the Ottoman sultan Ahmed I. It is located in the historical centre of Istanbul, near the Hagia Sophia, the Topkapi Palace, and the Grand Bazaar.

The Sultan Ahmed Mosque is known for its stunning blue tiles, which give it its nickname, and its six minarets, which make it a distinctive feature of the Istanbul skyline. 

The mosque's interior is also beautifully decorated, with marble columns, gold leaf, and intricate frescoes. The mosque is still an active place of worship and is open to visitors, who are welcome to enter and observe the prayers from designated areas.