In 1819, a troop of soldiers led by Colonel Henry Leavenworth established the first permanent Euro-American settlement in Minnesota on land ceded by the Dakota to Zebulon Pike in 1805. Leavenworth began building a fort at the junction of the Mississippi and Minnesota rivers, an area known to the Dakota as mendota (the junction of rivers). In 1820, Leavenworth was replaced with Colonel Josiah Snelling who finished the stone fort that today bears his name. Across the Minnesota River from Fort Snelling, a small group of traders led by Henry Sibley and Jean Faribault established a community known as St. Peters, later known as Mendota.
The military temporarily abandoned Fort Snelling in 1858, but reoccupied it at the beginning of the Civil war in 1861. By the late 1870s, a "new" fort began to sprawl to the south and the old stone fort was soon abandoned. The walls and some of the original buildings were torn down. By the early 20th century, only the round tower, the hexagonal battery, the officer's quarters, and the commandant's house remained.
When highway construction threatened the remains of old Fort Snelling in the early 1950s, the Minnesota Historical Society (MNHS) made a successful plea to save the site and began a 20-year reconstruction program to restore the fort to its 1820s look. The restoration was preceded with intensive archaeological excavations.
On the Mendota side of the river, the historic buildings were gradually abandoned after the Civil War. In 1910, the Daughters of the American Revolution purchased the dilapidated Sibley House complex and began restoration. Today the complex includes the Sibley House and the Faribault House. The nearby Church of St. Peter dates to 1842, although a new church was built adjacent to the old one in 1974. Archaeological excavations were carried out for MNHS in small areas of the Sibley complex in the 1980s and 1990s. MNHS took over operation of the Sibley Historic Site in 2003.
The Fort Snelling Historic District was listed on the National Register of Historic Places in 1966, although it had been designated a National Historic Landmark in 1960. The Mendota District was listed in 1970. Both the Sibley House Complex and Old Fort Snelling are open to the public and contain some archaeological interpretation. The numerous late 19th century buildings in the area known as the "new fort" or Upper Bluff have fallen into disrepair, but efforts are being made to restore and re-use them.
More information about the site: Fort Snelling and Sibley Historic Site web page