Unlike the other key sites in Istanbul, the Blue Mosque is an actual functioning mosque where worshippers show up to pray five times a day. As a result, non-believers may only enter the mosque between prayer times, so there are 90 minute windows where tourists line up by the hundreds to get in.
There are some rules about entering the mosque in terms of dress, head-coverings for women, and everyone must take off their shoes. But once you’re inside you’re rewarded with these sights. Fantastic, but ultimately not as blue as you would think.