The Sultan Ahmed Mosque (Turkish: Sultanahmet Camii; Tourist: Blue Mosque) is considered to be one of the last great classical mosques. It took seven years to build and was finished in 1619. It is built in the style of the Süleymaniye Mosque which was built a century earlier. The Sultan Ahmed Mosque is one of the few mosques with six minarets which are difficult to capture all together on the grounds of the mosque itself. I have a photo with five but it's full of trees. I've scoured Google Maps and I have a couple spots picked out to get them all on our next check-in to Istanbul!
It is called the Blue Mosque by tourists because of the blue tiles on the interior ceiling. I thought it would be more blue.
Like most mosques in Istanbul it is open to visitors outside of specific hours when it is in use.