The church is located in Dubuque, Iowa, United States, at the corner of 15th and White Streets.

Also, Bishop Mathias Loras was having difficulty ensuring that the German families were adequately cared for.

Gerhard Hueckels donated land at the corner of 8th and White Streets in Dubuque.

This church, named Holy Trinity, was built of native stone with a tower about twenty feet tall.

The people of Holy Trinity parish were served at first by a missionary, Father Gerhard Plathe.

In 1863, the pastor, Father George Fendrick, and members of the parish founded the "German Roman Catholic Association of Dubuque."

In 1914, stained glass windows built in Bavaria were installed in the church, though the shipment of the windows was nearly stopped because of the outbreak of World War I. Twelve large stained glass windows honor the Blessed Virgin Mary, and a large mural of the Assumption of the Blessed Virgin Mary was painted behind the altar, because the Assumption of the Blessed Virgin Mary is the patron saint of the parish.

In 1941, he was killed in the attack at Pearl Harbor, becoming the first American chaplain of any faith to die in the Second World War.

The parish removed the communion rail and placed a new altar in the sanctuary that faced the congregation.

The parish has been affected by the Priest shortage and a decline in membership as some families moved to suburban locations.

The parish had a priest to lead Mass, but most of the administrative work was handled by a lay woman minister, the wife of a former U.S. Representative who is a deacon.

The movie F.I.S.T., which was largely filmed in Dubuque, had a scene which featured exterior shots of St. Mary's Church.

[4] In 2014 a conceptual plan (but no timeline or cost estimate) to renovate the campus to provide office space for small businesses, a community kitchen and 12 units of low income housing was jointly announced by the Dubuque Archdiocese, non-Catholic community groups such as Dubuque's Economic Development Department and the Washington Neighborhood Corporation, and Dubuque-based Gronen Restoration.