Bucharest has the largest transport network in Romania, and one of the largest in Europe. The Bucharest transport network is made up of a subway network and a ground transport network. Although there are multiple connection points, the two systems operate independently of each other, and are run by different organisations (the subway is run by Metrorex and the ground transport network by Societatea de Transport București. The two companies used separate ticketing systems until 2021, when a new smartcard was introduced alongside the old tickets, which allows travel on both the STB and the Underground.