Barcelona had an extensive tram network from 1872 until 1971; by the latter year all but one line had been replaced by bus or metro lines, and the remaining line was primarily a tourist attraction. In 2004, two separate tram systems, Trambaix and Trambesòs opened. Although they are not connected, they use the same rolling stock, are part of the regional ATM fare structure, and there are plans to build a line on the Avinguda Diagonal that would link the two networks.