The most popular form of public transport in Nairobi are matatus, minibuses that operate on set routes. Cheap but unregulated, these overcrowded vehicles have become part of Kenyan culture. No less risky are the local bus services, renowned for speeding and dangerous driving.Taxis are widely available and convenient, usually congregated around hotels and areas frequented by tourists. They aren't metered and the fare should be agreed upon before departure. Nairobi taxis are marked with a yellow line along the side of the vehicle, or appear as large black London taxis.The better taxi companies have more modern vehicles, which can be booked by telephone. The best option if you are spending a day or two in the city is probably to hire a taxi and driver recommended for you by your hotel or tour operator. Three-wheel auto-rickshaws, or tuk-tuks, are also used as taxis in Nairobi. Walking in the city can be dangerous and is not a good idea after dark or outside of tourist areas.