Katowice–Ostrava metropolitan area

The Katowice–Ostrava metropolitan area (also known as Upper Silesian-Moravian metropolitan area[a] or Upper Silesian urban-industrial agglomeration) is a polycentric metropolitan area in southern Poland and northeastern Czech Republic, centered on the cities of Katowice and Ostrava, and has around 5 million inhabitants. Geographically, it is located mainly in Upper Silesia, with small parts of the area also in the historical regions of Moravia and Lesser Poland.

Source: Wikipedia — Katowice–Ostrava metropolitan area (CC BY-SA 4.0)