Melbourne's efficient public transport system is an integrated service utilising trams, trains and buses, with standard fares. The best way to see the city and central suburbs is by tram, a fast, cheap and convenient system that is one of the largest and oldest in the world. The Free Tram Zone was established in 2015 and provides free transportation around the CDB. In addition to this, the City Circle tram route loops around the CBD's perimeter. It provides a commentary and the trams are a very convenient way to tour the city centre, providing a service that passes many of the city's main attractions. The suburban train network is extensive and is the fastest way to reach outlying suburbs, and also has an underground city loop. Buses cover the areas that trams and trains don't reach, as well as those they do, but are little used by visitors; on weekends there is a limited night bus service. Taxis, highly visible in bright yellow, are numerous but expensive. Car hire companies are available throughout the city.