Saint Nicholas Cathedral is the only surviving building of Ochakov from Turkish times. The former mosque is the only surviving building of Ochakov from Turkish times. It was turned into an Orthodox church in 1794, after the capture of the city by Russian troops. At first a wooden dome was added, and in 1804-07 a major reconstruction was carried out: a stone altar, vestibule and porch were added, and the stone minaret was converted into a bell tower.
From the time of its construction until the beginning of the XX century St. Nicholas Church in Ochakov was the main army religious building. It was called St. Nicholas Naval Cathedral. Such a status it received with the light hand of military commanders, under whose command in 1788 Ochakov fortress was taken by storm from the Turks. 
For the next few decades the church was subordinated from one military department to another. The clergy, for their part, tried to emphasize in every possible way the belonging of the church to the military department, carefully keeping the sacred things received as a gift immediately after the capture of the fortress in 1788.
Like most wooden structures, the building of the cathedral became dilapidated over time and was replaced by a stone one.
After the revolution, the temple continued to operate for some time, but the new authorities gradually and persistently continued to ruin it. The shrines belonging to the temple and representing historical value were taken away, ostensibly to help the hungry. 
And in 1930, by decision of the Presidium of the Ochakovsky District Executive Committee, the church was closed, the bells were removed, and the building itself was transferred to the disposal of the Nikolaev Regional Museum of Local Lore, which opened its branch, giving it the status of the Suvorov Military History Museum in 1966. In 1972, the artist M.I.Samsonov created a diorama «Storming of the fortress Ochakov«.
At the end of the XX century the museum moved, and the structure was returned to the bosom of the Ukrainian Orthodox Church. But, to the regret of descendants, its cultural heritage of great historical value was irretrievably lost.