Old Mission State Park, located in North Idaho near the town of Cataldo, is a historic site featuring the oldest building. The main feature of this park is the Sacred Heart Mission or Coeur d'Alene's Old Mission, which was constructed by Catholic missionaries and members of the Coeur d'Alene Tribe between 1850 and 1853.

Spanning approximately 22 acres along Interstate-90 east of Coeur D'Alene Lake, it offers visitors not only historical insight but also scenic beauty with picnic areas and interpretive trails. Designated as a state park on August 8th, 1987 during its centennial celebration (though established much earlier), it serves to preserve an important piece of both Native American history and early missionary work in what would become Idaho.