The cornerstone, located at the northeast corner of the building, bears the dates "1872", the start of construction, and "1878", the year of completion. The stone was opened during ceremonies November 15, 1978, the centennial of the building's completion. Various documents enclosed within the stone had been damaged by moisture, although several coins from the era remained intact. Officials closed and resealed with stone with 38 new items depicting Michigan's history, people, and lifestyles. At the lawn's southeast corner is the Grand Army of the Republic Memorial, a 1924-bronze plaque attached to a boulder as a memorial to American Civil War veterans who fought for the Union.