The City of Ste. Genevieve sits on the west bank of the Mississippi River, about two miles north of the original village settled in the 1740s by French Catholics who crossed the river from the French settlement of Kaskaskia, in what is now Illinois. The Catholic community, originally known as St. Joachim, was served by missionaries with Mass celebrated in the homes of the settlers.
The first church, a log structure, was built in 1759, close to the river in an area known as Le Grand Champ or The Big Field.
Jesuit Father P.F. Watrin, who as a missionary there helped found the parish, became its first pastor. The parish and town became Ste. Genevieve, named after the saint who saved Paris from an attack by Attila the Hun in the fifth century.
Catholics continued to attend the log church until after the Mississippi flood of 1785. Although the church building survived the damage incurred from the flood, it was decided to move the church to the new town location in 1793, with parts of the building moved and new material supplied by parishioners to reconstruct and enlarge the building.
Link (here) to the full article in the St. Louis Review