Istanbul's ancient history is revealed in its architecture, which includes the Haghia Sofia, built in the 532 as a magnificent Catholic basilica and converted into a mosque in 1453.But the city known today as Istanbul was founded by the Greeks in 657 BC and incorporated by the Roman empire in 64 BC. Back then it was known as Byzantium. When the Roman emperor Constantine declared it to be his capital in 430AD , it was renamed Constantinople and over the next 11 centuries many magnificent palaces and churches were built, including the Haghia Sofia, which today is a museum.
Many of the people living in Istanbul are Muslim and the call to prayer is heard five times a day, at which time everyone goes to the nearby mosque to pray. Ordinary people can visit mosques, except at prayer time, but must do as the Muslims do before entering: leave their shoes behind and wash hands and feet.

Turkey has been a secular country since the 1920s, so Muslims there look like you and me...jean, tennis shoes and all but fewer tattoos...but perhaps that's becausue they also expose less skin then Americans seem to for for the most part.  We saw no men in robes and only a few scattered women wearing burkas. Veiled women were seen of course, but probably no more than would be seen in Detroit, which has a large Muslim population. It's a country with a long history of being home for many different religions and tolerance is the way of doing things.