Almost opposite the Sublime Porte we see the Alay Köşkü, or Review or Parade Pavillion, a polygonal gazebo from whose latticed windows the Sultan could observe the comings and goings at the palace of his Grand Vezir. The aptly named Sultan Crazy Ibrahim was said to pick off passing pedestrians with his crossbow. The present construction dates from 1819, when it was rebuilt by Sultan Mahmut II, but at the spot of earlier versions.

Source: Strolling through Istanbul