Leipzig was first mentioned in a document in 1015. t is located at the intersection of two important medieval trade routes: Via Regina and Via Imperii. For centuries it was an important centre of trade and trade fairs. There still is the annual Leipziger Buchmesse (Leipzig Book Fair). Leipzig today is an important finance centre. The Leipzig university was founded in 1409. Both Johann Sebastian Bach and Felix Mendelssohn-Bartholdy lived and worked in Leipzig. The Thomaskirche is a late-Gothic hall church of the Lutheran Church of Saxony . In 1989 the Monday Demonstrations started at the Nicolai Church in Leipzig. Bach was Cantor at Thomas Church.