Visitors to Houston are well advised to hire a car, which is relatively inexpensive and provides the quickest and most convenient way to navigate the spread-out city. There are plenty of car parks and a well-managed road system. To hire a car (for up to 90 days), a full national driver's license is required and drivers must be at least 25 years old (some companies hire cars to those aged 21 to 24 with surcharges).Those opting for public transport will find that the METRO has it well covered with an efficient and extensive bus service, as well as a light rail line which links Downtown, Midtown, the Museum District, Hermann Park, the Texas Medical Center, and Reliant Park. Correct change is required for on-board bus fare boxes, or purchase tokens or a day pass in advance from local stores sporting the Metro sign. Taxis are a rather expensive option, though readily available downtown.