The Bali Süleyman Ağa mosque and its Külliye (complex of buildings with a mosque) is located on the Tekke Street at Silivrikapı Veledi Karabaş. On the place where this complex is now a prayer room with masonry walls and wooden roof had been built, in memory of Sÿleyman Ağa who was an artilleryman during the conquest of Istanbul. He had the honour, the notice on site tells us (which twice reads Bala instead of Bali), of receiving our Prophet’s praises, and was buried at the mausoleum next to the mosque. Both the prayer room and the Tekke were rebuilt between the years 1862-62 (the era of Abdulaziz) to be used as a tevhidhane, in a much bigger way with a dome. A Tekke is, according to Wikipedia, a gathering place of a Sufi order, or the shrine of a saint. I have been informed the word tevhit or tevhid means "unity". A Tevhidhane is a "house of unity" (with Allah). In the Mevlevi-orders it is the place where ritual ‘dances’ are performed. Also called ‘semahane’. Not every ‘Tekke’ has a large enough room to hold one.
At any rate, when I arrived, a service was going on but I was invited in and took some pictures. I have often passed this place but always found it closed. Some of the pictures are of adjacent buildings, I think some may be of the Tekke.