Gol Gumbaz, the famous mausoleum of Muhammad Adil Shah with the world's second-largest dome, is located in Bijapur (now Vijayapura), Karnataka. Built in 1656, it's an iconic Deccan Sultanate monument. Gulbarga has its own monuments but not Gol Gumbaz. Hyderabad and Secunderabad are in Telangana with different architectural heritage.