Why do you think Romanesque temples resembled fortresses?

The Romanesque style in architecture spreads in the countries of Western Europe in the 9th-12th centuries. The style is notable for its massiveness, severity, severity of appearance. Temples resemble impregnable fortresses with massive walls, narrow loophole windows, high towers. Due to their inaccessibility, Romanesque churches could withstand a siege during the period of internecine wars, serve as a refuge during the war. The most famous buildings of the Romanesque style are Libmurg Cathedral in Germany, Pisa Cathedral in Italy, St. Jacob in Regensburg and others.