From the Wikipedia page 
Poznań (/ˈpoʊznæn, -nɑːn/ POHZ-na(h)n; Polish: [pɔznaɲ]; German: Posen; known also by other historical names) 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 and Ostrów Tumski Cathedral. Today, Poznań is an important cultural and business centre and one of Poland's most populous regions with many regional customs such as Saint John's Fair (Jarmark Świętojański), traditional Saint Martin's croissants and a local dialect.
Poznań is among the oldest and largest cities in Poland. The city population is about 550,000, while the continuous conurbation with Poznań County and several other communities is inhabited by almost 1.1 million people. The Larger Poznań Metropolitan Area (PMA) is inhabited by 1.3–1.4 million people and extends to such satellite towns as Nowy Tomyśl, Gniezno and Września, making it the fourth largest metropolitan area in Poland. It is the historical capital of the Greater Poland region and is currently the administrative capital of the province called Greater Poland Voivodeship.