Firuz Aga Mosque was constructed by Firuz Aga who was the Chief-treasurer of Sultan Bayezid II. The mosque with a bigger yard before the extension of Divanyolu, was constructed in 1491 as it was shown at the tablet on its door. The script at the tablet was written by Sheikh Hamdullah Efendi. The mosque that is a typical small mosque with a single dome and a simple mixture of Bursa style has square plan. Four sconces were constructed at the upper part of four edges formed by the walls inside and therefore the dome was settled on an octagonal frame.
The mosque has no inner court. It was made up of face stone and the dome frame has 12 edges and it is flat. At each wall, there are two windows at the bottom and top. The depth of the narthex is 4.25 m. and it has three domes. The column heading of this part is made up of drop stone. The main door is somewhat ribbed and it has a simple wiped frame. The edges of the door has round-like flat arch, and are made up of white and pink marble. On the arch there is a tablet of four-spaced in two lines and above this simple almonds are processed. At the center there is a rosette and at the sides there are two geometrical Mohammed script that are exactly similar to each other.
The single balcony minaret of Firuz Aga Mosque is on the left and the boot at the body is extremely short and chequered. The difference of dimension between the body and base is so few. The balcony and railing are in classical style. Firuz Aga’s tomb does not exist in our day. The tomb was destructed with the command of Grand Vizier Kececizâde Fuad Pasha during the extension of Divanyolu, the marble coffin of Firuz Aga is located in front of the left wall where the minaret is present, and it is at the clearance. The cemetery of the mosque was totally removed.