Poznan is a city on the Warta river in west-central Poland, in the Greater Poland region. It is best known for its renaissance old town, destroyed during World War II and then rebuilt, and Ostrow Tumski cathedral. Today, Poznan is an important cultural and business centre and one of Poland's most populous regions with many regional customs such as Jarmark Swietojanski, traditional Saint Martin's croissants and a local dialect.