If you research the Luxembourger community at Belgium, Wisconsin, the Port Washington Historical Society should be among your research stops. A relatively new historical society, the Port Washington Historical Society was established in 1991. From the looks of their website, they have built quite an impressive collection in that time.
Their research center includes many resources for Luxembourger families. They have archival files on the local churches, including St. Mary's, photographs and more. If you wish to access the collection yourself, you will have to visit the Luxembourg-American Cultural Center. However, the Historical Society does do research for a fee.
If you're only interested in digital resources, check out their historic maps. Available online are images of the area from the late 1890s.