The following is a timeline of the history of the city of Basel (or Basle, in the once-preferred English spelling). Established in the 4th century, the city rose to importance in the medieval period as a bishop's seat. In the 15th century it became an important center of Renaissance humanism and, in the 16th century, of the Protestant Reformation.Basel joined the Swiss Confederacy in 1501. In the 19th century, Basel was a center of Industrialisation, and it remains one of the major cities of contemporary Switzerland.