Church of Saint Andrew

The Church of St. Andrew in the Old Town district of Kraków, Poland located at Grodzka Street, is a historical Romanesque church built between 1079 and 1098 by a medieval Polish statesman Palatine Sieciech. It is a rare surviving example of the European fortress church used for defensive purposes.

Built in Romanesque style, it is one of the oldest buildings in Kraków and one of the best-preserved Romanesque buildings in Poland. It was the only church in Kraków to withstand the Mongol attack of 1241. Along the lower part of the broader section of its façade are small openings that served as defensive windows at a time when the church was a place of refuge from military assaults.

Source: Wikipedia