Johannesburg is a huge city. O.R. Tambo International Airport is Johannesburg's main airport. It is the busiest airport in Africa as it is the connecting hub for flights to South Africa. For this reason there are many cheap flights to Jo'burg from major cities all over the world, especially cheap flights to Johannesburg from London UK as well as numerous local flights on a daily basis. The flights to Johannesburg are cheaper because of the route being busy and the airlines have competitive fares. The airport is located east of Johannesburg, 24 km (15 mi) from the city center. It's a quick drive by hotel shuttle, hired car or taxi to your destination. It is advisable to buy some SA Rands before you leave home, as the exchange rates at the airport tend be unfavourable than general high street Bureau de Change. Lanseria Airport is mostly used for regional, corporate passage. There are however regular flights from this airport to Cape Town. A number of highways from everywhere in South Africa lead to Johannesburg. Highways are N1 from Cape Town and Harare in Zimbabwe ,N3 from Durban, N4 from Nelspruit and the Kruger National Park, as well as Botswana, N12 from Kimberley and Potchefstroom and N14 from Upington and Namibia. Park Station is Johannesburg's central station. Long distance trains running out of Johannesburg are Spoornet trains and MetroRail trains. Long distance buses also arrive in and depart from Park Station. Major bus companies are  Greyhound, Translux, Magic Bus, S.A Roadlink and The Baz Bus. Public transport in Johannesburg is provided by Large Blue City buses(running up and down main roads) and informal minibus services(not very reliable).