The Rock Island Arsenal comprises , located on Arsenal Island, originally known as Rock Island, on the Mississippi River between the cities of Davenport, Iowa, and Rock Island, Illinois. It lies within the state of Illinois. The island was originally established as a government site in 1816, with the building of Fort Armstrong. It is now the largest government-owned weapons manufacturing arsenal in the United States. It has been an active manufacturer of military equipment and ordnance since the 1880s. In 1919-20 100 of the Anglo-American or Liberty Mark VIII tanks were manufactured, although too late for World War I. It is designated as a National Historic Landmark.