The oldest standing building in the state of Idaho is the Mission of the Sacred Heart, or otherwise known as the Old Mission State Park. This site is also a historical landmark located in the community of Cataldo in northern Idaho.

The state park contains the historic church, parish house, and surrounding area. In 1850, a new mission building was proposed by Antonio Ravalli, a priest who led the mission. He made sure that the building was constructed with the help of the Indians he was converting to make them feel part of the church. Without using a single nail, the new church was built for three years using wattle and daub method.

The mission also historically served as trading posts for merchants, miners and settlers who pass by or live around the mission area. The church and the site were declared a National Historical Landmark on July 4, 1961.