Our Lady of Assumption Co-Cathedral or the Co-Cathédrale de Notre-Dame-de-l’Assomption is located in the Canadian prairie town of Gravelbourg, Saskatchewan.

On September 14, 1998, Pope John Paul II suppressed the Diocese, merging it with the Archdiocese of Regina—a reflection of the steady depopulation of rural Saskatchewan.

According to the Archdiocese of Regina website, "The architect, J. E. Fortin of Montreal, chose a style that combines Romanesque and Italian Renaissance.

The building is steel frame with outer walls of tan-coloured brick trimmed with Indiana stone.

The nave interior was altered in the 1960s to bring the church into conformity with the liturgical requirements issued by the Second Vatican Council.