Complex sentence: When the Reformers attacked the abbey church in March 1560, they spared the nave, which served as the parish church till the 19th century, and now forms the vestibule of the New church.
Split into simpler sentences: When the Reformers attacked the abbey church in March 1560, they spared the nave. It served as the parish church till the 19th century, and now forms the vestibule of the New church.