The Blue Mosque was built in Istanbul in the early 1600s for an Ottoman sultan. It has an ornate interior with over 20,000 blue Iznik tiles lining the high ceiling, which gives the mosque its name despite having a plain exterior. The mosque features six minarets instead of the more common four, which was controversial at the time as some thought it was trying to outdo the mosque in Mecca. Domes and enormous interior columns support the central space and allow light to shine through the hundreds of windows.