Complex sentence: The new church was built according to architects Henri Colboc and Jean Dionis du Séjour plans on former quarries and had to be anchored by deep masonry to reach solid rock.
Split into simpler sentences: The new church was built according to architects Henri Colboc and Jean Dionis du Séjour plans. It was built on former quarries and had to be anchored by deep masonry to reach solid rock.