Hagia Sophia, also known as Ayasofya in Turkish, is one of Istanbul’s most iconic landmarks and a symbol of the city’s rich history and cultural heritage. Here’s an overview of Hagia Sophia:

1. History: Originally built as a Christian cathedral during the Byzantine Empire in the 6th century AD, Hagia Sophia was constructed under the orders of Emperor Justinian I and completed in 537 AD. It served as the seat of the Eastern Orthodox Church for nearly a thousand years.
2. Architecture: Hagia Sophia is renowned for its architectural grandeur and innovative design. It features a massive dome that was considered an engineering marvel of its time, supported by pendentives and massive buttresses. The interior is adorned with intricate mosaics, marble pillars, and decorative elements reflecting both Byzantine and later Ottoman influences.
3. Conversion to a Mosque: Following the Ottoman conquest of Constantinople (Istanbul) in 1453, Hagia Sophia was converted into a mosque by Sultan Mehmed II. Islamic architectural elements such as minarets, mihrab (prayer niche), and minbar (pulpit) were added to the structure.
4. Museum: In 1935, Hagia Sophia was converted into a museum by the Republic of Turkey under the leadership of Mustafa Kemal Atatürk, as part of efforts to secularize the country and preserve its cultural heritage. It was opened to the public as a museum in 1935, showcasing both Christian and Islamic elements of its history.
5. Status Changes: In July 2020, Hagia Sophia underwent another significant transformation when Turkish President Recep Tayyip Erdoğan announced that it would revert to a mosque. Following a court ruling, regular Muslim prayers resumed at Hagia Sophia, and it once again became a functioning mosque.
6. Visiting: As of my last update in January 2022, Hagia Sophia is open to visitors, allowing them to explore its historic architecture, mosaics, and artifacts. However, it’s essential to check the latest information regarding visiting hours, ticket prices, and any restrictions due to ongoing events or renovations.

Hagia Sophia remains a symbol of Istanbul’s complex and layered history, reflecting its role as a meeting point of different cultures, religions, and civilizations over the centuries.