This mosque is located in Old town (Kastel), not far away from the main (west) entry gate and town walls. It was built of masonry stone and covered with four-part roof resembling a dome, which is covered with fiber cement. Along the right wall an octagon shaped stone minaret was built, 16 meters tall, and it was one of the most beautiful in whole Herzegovina. It came into being in 1726 as Osman-pasha’s legacy to Trebinje. It was constructed by architects and builders from Dubrovnik, with certain elements of Mediterranean architecture. It is considered the most spacious mosque in Herzegovina. Prior the war it was a cultural monument under Republic protection. Osman-pasha also built maktab and madresa near the mosque, and they were first educational objects in Trebinje.
After the construction, Osman-pasha was accused in Istanbul for building a more beautiful mosque in his name than in emperor’s (Emperor’s mosque). That is why sultan Ahmed III issued an order to execute him and his nine sons. Osman-pasha went to Istanbul to beg for pardon but with no success, so he was executed in 1729.