According to the chronicler Jan Długosz, the church in Kotłów was founded in 1108 by Piotr Włostowic, a palatine of the prince Bolesław Krzywousty. The romanesque temple survived unchanged until 1721. At that time a tower was added from the west. Another reconstruction took place in the years 1905-1908, when the apse was moved to the east, adding a transept. In 1923, the tower received a form preserved to this day.
The romanesque church was a orientated, aisleless church with a short chancel ended by a semicircular apse. It was built of stone blocks connected with lime mortar. The 1 meter-thick walls rose to a height of about 9 meters.
Inside the temple, elements of romanesque architecture have been preserved. In the eastern wall of the romanesque church there are remnants of the old side altars with ciborias, that is with brick canopies. It was a unique solution used in the Polish church. There are stone crosses on both sides of the altar, and on the right side of the nave, there is a walled stone with the bas-relief of walking lion, which according to the local legend is to depict a pagan god who was once worshiped on the nearby hill. During the excavation works, the remains of the 12th-century romanesque crypt were also discovered.
Webpage regionwielkopolska.pl, Kościół pw. Narodzenia NMP w Kotłowie.