St. Anthony’s Church is the largest Catholic church in Turkey. The facade of the church is built with red bricks. It was built in a Neogothic style by Italian Architect Giulio Mongeri. The church has the largest Christian community in Istanbul, and believers of all kinds of religions frequently visit it. Pope John XXIII Before being elected Pope, John preached here for 10 years while he was the Vatican’s Ambassador to Türkiye.