Hello Steemians,
Today I am going to tell you about Sultanahmet mosque which is called as Blue Morque.
This mosque is constructed by Architect Seferi Mehmet Ağa between 1609-1616 years. The architect inspired from Maqqa mosque where is in Saudi Arabia. In that years, The ottomon empire was leading Saudi Arabia and The architect criticized too much because of similarities between these two mosque. So Sultân 1. Ahmet commanded to add one more minarets to finish conflicts about similarities. 
In the entrance of this mosque there is a very meaningful sentence. ' Whoever gets inside of the Mosque he/she has to bend their body even he is a sultan or Padishah because it is home of Allah' is written on cordon.
Entrance is free and you don't have to pay a fee. But there are two main rules for entering. First one; it is a religious place so you have to care about clothes I mean you shouldn't enter with open body. Second rule is; during the Cuma prayer, you are not allowed to enter for not to disturb Society while they are praying.
The speciality of the Mosque is when it constructed; the architect have used 32.000 kinds of Tile motives which have many different flower effects. When you enter, you're going to be amazed by beauty of Tile motives.
As an end, I recommend you to visit Blue Mosque if you have a chance to visit Istanbul even you have limited time.