When Fort Snelling was built in the early 1820's it was the Army's last outpost in the Northwest. The fort was a key site in trade with the Native Americans and played a key role in the settlement and development of the Twin Cities area. The fort was used for training during the Civil War and remained an active Army base through World War II.
If you go:
Tours are offered during summer months, with exhibits on pioneer life in the region. The fort is now surrounded by a State Park with the same name, offering miles of trails along the banks of the Mississippi and Minnesota Rivers.
Links:

200 Tower Avenue
St. Paul, Minnesota 55111 USA
ftsnelling@mnhs.org
Phone Numbers:
Fort Snelling Historic Site
+1 (612) 726-1171
+1 (612) 726-1171
Fort Snelling State Park
+1 (612) 725-2389
+1 (612) 725-2389