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 Paulinerkirche was the old University Church of Leipzig – built in 1231 in Gothic style. It survived World War II nearly undamaged. But it was blown up in an act of purist barbarism by the communist regime in 1968. The new Paulinum was built on the old site in 2007.