This is an example of the first stage of single-domed mosques in which Sinan
managed to widen the interior space by adding two buttresses to each side wall.
It prefigures the octagonal based dome plan Sinan was later to realise. The
smooth passage from the walls to the dome is ensured by trompes invisible from
the outside. This mosque's plan bears a striking resemblance to that of the Bali
pasha Mosque, the dates of which are not clearly established.
Above text and pictures are from the book titled "Turkish Art and Architecture in Anatolia and Mimar Sinan".
You can purchase "Turkish Art and Architecture in Anatolia and Mimar Sinan" book and other Turkey related books from Explore Turkey Bookstore.