[2] The church was added to the National Register of Historic Places in 1977 for its architectural and religious significance.

[1][3] The first Catholic Mass in Port Washington was read in Franz Gengler's home in 1847.

[4] In 2016, St. Mary's officially merged with St. Peter of Alcantara in Port Washington and Immaculate Conception in Saukville to become St. John XXIII Parish.

A large tower is in the front center, with the main entrance at its base and a rose window above it.

[4] In 1883 at the new church's dedication, a speaker described the building as "a splendid structure, an ornament not only to the city, but the entire state."