Seinajoki is a city located in Southern Ostrobothnia, Finland. Seinajoki originated around the Ostermyra bruk iron and gunpowder factories founded in 1798. Seinajoki became a municipality in 1868, market town in 1931 and town in 1960. In 2005, the municipality of Peraseinajoki was merged into Seinajoki, and in the beginning of 2009, the neighbouring municipalities of Nurmo and Ylistaro were consolidated with Seinajoki. The Town library, Lakeuden Risti Church and central administrative buildings are designed by Alvar Aalto.