Blue Mosque interior panorama. At its lower levels and at every pier, the interior of the mosque is lined with more than 20,000 handmade İznik style ceramic tiles, made at Iznik (the ancient Nicaea) in more than fifty different tulip designs. The tiles at lower levels are traditional in design, while at gallery level their design becomes flamboyant with representations of flowers, fruit and cypresses. The tiles were made under the supervision of the Iznik master. The price to be paid for each tile was fixed by the sultan’s decree, while tile prices in general increased over time. As a result, the quality of the tiles used in the building decreased gradually.
The upper levels of the interior are dominated by blue paint. More than 200 stained glass windows with intricate designs admit natural light, today assisted by chandeliers. On the chandeliers, ostrich eggs are found that were meant to avoid cobwebs inside the mosque by repelling spiders. The decorations include verses from the Qur’an, many of them made by Seyyid Kasim Gubari, regarded as the greatest calligrapher of his time. The floors are covered with carpets, which are donated by the faithful and are regularly replaced as they wear out. The many spacious windows confer a spacious impression. The casements at floor level are decorated with opus sectile. Each exedra has five windows, some of which are blind. Each semi-dome has 14 windows and the central dome 28 (four of which are blind). The coloured glass for the windows was a gift of the Signoria of Venice to the sultan. Most of these coloured windows have by now been replaced by modern versions with little or no artistic merit.
The most important element in the interior of the mosque is the mihrab, which is made of finely carved and sculptured marble, with a stalactite niche and a double inscriptive panel above it. It is surrounded by many windows. The adjacent walls are sheathed in ceramic tiles. To the right of the mihrab is the richly decorated minber, or pulpit, where the imam stands when he is delivering his sermon at the time of noon prayer on Fridays or on holy days. The mosque has been designed so that even when it is at its most crowded, everyone in the mosque can see and hear the imam.
The royal kiosk is situated at the south-east corner. It comprises a platform, a loggia and two small retiring rooms. It gives access to the royal loge in the south-east upper gallery of the mosque. These retiring rooms became the headquarters of the Grand Vizier during the suppression of the rebellious Janissary Corps in 1826. The royal loge (hünkâr mahfil) is supported by ten marble columns. It has its own mihrab, which used to be decorated with a jade rose and gilt and with one hundred Qurans on an inlaid and gilded lecterns.
The many lamps inside the mosque were once covered with gold and gems. Among the glass bowls one could find ostrich eggs and crystal balls. All these decorations have been removed or pillaged for museums.
The great tablets on the walls are inscribed with the names of the caliphs and verses from the Quran. They were originally by the great 17th-century calligrapher Seyyid Kasim Gubari of Diyarbakır but have been repeatedly restored.