FRONTENAC, Minn. (CNS) — On the side of U.S. Highway 61 near Frontenac State Park sits a limestone historical marker surrounded by prairie grasses on the edge of an old oak forest.

The marker is a tribute to Fort Beauharnois, established in September 1727 and considered to be the last French fort in operation along the Mississippi River.

As the historical marker indicates, “a party of French soldiers and traders under the leadership of Rene Boucher Sieur de la Perriere built a fortified post on Lake Pepin from which they traded for two years with the Dakota (Sioux) Indians.”

“They were there,” it adds, “to secure an alliance with the Dakota in order to gain access to the fur and possible mineral wealth of the area and to eventually press westward in search of the ‘great western sea.'”

Thought to have been constructed along Lake Pepin, the original fort is believed to have included a stockade and a series of log buildings — including Minnesota’s first Catholic chapel, the Mission of St. Michael the Archangel. It was erected by Jesuit missionaries Fathers Michel Guignas and Nicholas de Gonner, who were accompanying the expedition.

Historians believe the fort and mission were abandoned in 1756. Although a series of archaeological investigations have been conducted over the years, the location of the fort and the Catholic chapel has never been found.

The unknown location of the state’s first Catholic chapel piqued the interest of George Pett, a parishioner of Immaculate Heart of Mary in Minnetonka, Minnesota.

For the past five years, Pett, 72, has ventured to the Frontenac area to explore, and hopefully discover, artifacts and other indicators of the fort and chapel’s location.

“One day my family and I were driving down Highway 61 toward Lake City and saw a historical marker. We pulled off, went up to the monument and read the plaque,” Pett told The Catholic Spirit, newspaper of the Archdiocese of St. Paul and Minneapolis.

“A few years later, we were driving down the same highway and I stopped again at the marker and I thought, ‘Why hasn’t this been found? This should be found!'” he said.

Pett, who became a Catholic 10 years ago, retired two years ago after 50 years in the financial services industry and began his quest to discover the location of the fort and chapel. He said his faith has compelled him to do what he can to uncover the mystery surrounding the state’s first Catholic entity, visiting the area a handful of times each year.

Considering himself to be an “avocational archaeologist,” Pett has spent half a decade researching and exploring the area.

Using a metal detector and other tools, he has found a handful of china shards, nails and Native American arrowheads. He has used maps of the area and a variety of resources at the Minnesota Historical Society, as well as done online searches and had conversations with a number of archaeologists in trying to pinpoint the site.

As Pett explained, the fort is believed to have been built on a hillside overlooking the Mississippi River near Sand Point in Frontenac State Park along Lake Pepin, 12 miles south of Red Wing, Minnesota. Historians believe the fort was flooded out in the spring of 1728 and rebuilt twice on higher ground before being abandoned during the French and Indian War.

“Myself and some historians believe the fort may be located on the campus of the former Catholic girl’s school and convent, Villa Maria Academy in Frontenac, which has been closed and sold to a St. Paul developer, who is renovating the school and convent into a luxury hotel,” Pett said.

“In 1976, the Minnesota Historical Society did a large survey of the area but did not find anything related to the fort,” he said. “They found a lot of prehistoric items as well as Native American artifacts, but nothing of French origin. However, one caveat of the original survey was that they only searched a handful of properties, none of which included the Villa Maria 140-acre property.”

The archaeological survey indicates the historical society conducted an extensive study, and many historians believe the fort might be on the former Villa Maria property, which until recently was owned by the Ursuline sisters.

Pett called the state of Minnesota to inquire about exploring Frontenac State Park using a metal detector to search for the traditional hand-forged iron items that would typically be used in a fort of that era. Pett was told that he could search, but he couldn’t dig if he got any “hits.”

So, he turned his attention to the Villa Maria property, which was purchased by developer John Rupp, who happens to be Pett’s former high school classmate and friend.

“So I called John up and explained what I was interested in doing, and he said, ‘Sure, you can explore the land and metal detect all you want,'” Pett said.

The Villa Maria campus had two parts — an upper portion that featured the convent and the site of the original 1890 school, the Academy of Our Lady of the Lake (later renamed Villa Maria Academy), which burned down in 1969. The lower portion of the property included woods, a ravine and hillside.

“Mother Superior Mary Kostha Bowman, whose father donated all the money for the school to be built, claimed she found some French items on the property. She had them on display in the school but they were lost in the fire,” Pett said.

Metal detector in hand, Pett has been exploring the property. The most interesting things Pett has found were located near the property’s Our Lady of Lourdes grotto — an arrowhead, some fool’s gold and a scraping tool traditionally used by Native Americans.

He has also found some nails, broken china shards and other items on other areas of the property. These items could be from farming activity or a French trading post that was in the area.

As to whether he will keep searching, Pett said that he is drawn to uncovering the unknown and finding the location of Minnesota’s first Catholic chapel.

“It’s truly amazing that more interest hasn’t been shown in discovering this chapel and fort,” Pett said. “I’m just going to see what happens as I continue to explore.”