Antwerp operates a premetro public transit system (known locally as "the metro"), which translates as a tram network that runs partly underground for some of its routes. Consequently, it isn't the fastest public transport in the world, but given the size of the city it doesn't need to be. It is, however, extensive and reliable. The most useful line for visitors (No. 9) links Centraal Station (metro: Diamant) with the left bank, which is the other side of the river (Linkeroever), via the Groenplaats (for the cathedral and Grote Markt). A €3 ticket (bought on board or via ticket machines) is good for one hour on all forms of public transport, including buses. Cheaper €2.15 tickets are available by SMS (see "Bus Travel"). A €6 (€8 bought on board) pass buys unlimited travel for one day. Tickets are available at De Lijn offices, the tourist office, and at the Diamant, Opera–Frankrijklei, and Groenplaats metro stops. The metro system is open 6:30 am–midnight (1 am on Friday and Saturday). Stations are marked by large arrows indicating the entrances.