The 'imperial mosque', as locals call it, was built on the orders of Mehmed the Conqueror around 1461, and although it was converted to a Catholic church during the Austro-Hungarian era, it was renovated again after WWII and is now the city's most important mosque. The minaret collapsed during an earthquake in 1955; the one standing today is a reconstruction. It has some beautiful interiors, as well as striking painted ceilings over the main entrance.