In front of the Pettigrew Home & Museum in Sioux Falls, SD is a 3-ton prehistoric prayer rock that was transported from near Mobridge, SD. Its exact age, purpose and creators are unknown but it does predate all the local Native American tribes known to have lived in the Dakotas. R. F. Pettigrew, the first state senator for the new state of South Dakota turned his passion for history and archaeology into a small private museum based in his elegant Queen Anne style home. This prayer rock was moved at his request to his home/museum and set up in 1925.