In some of the major cities of Spain, an underground Metro system operates with great success and avoids the traffic congestion above ground. However, at peak times some can become overcrowded. There is no smoking is allowed on the Metro or the underground stations, which is line with the general no-smoking in buildings and some public places, in Spain.
Madrid has one of the best transportation systems in Europe. Even with its large population navigating the public transportation system and getting around is easy. If you are going to stay in Madrid for a few days, get the 10 rides pass. Most ticket attendants don't speak English, but you'll get a ten usage pass by just saying the number "10" in Spanish. If you're going to use the Metro, it's smart to get a map of the metro system before you go; most books include one.
The Barcelona Metro is the most convenient way of Travelling around that city. The metro is made up of five interlinking lines. Trains run on these lines at intervals of around six to seven minutes.
There is a second subway system called the FGC (Ferrocarrils Generalitat de Catalunya) whose lines reach out to distant parts of the city as well as surrounding towns. Tickets can be purchased in Metro and FGC stations as well as at newspaper kiosks and lottery shops.
There are a number of cities which have Metro systems including Malaga which currently has two routes - one to the Sports complex and one beach area and another to Hospital Clinico, University and the Technology Park, both starting from close to the main railway station. Work is also in progress to extend this system to most of the city. Metro trains run on these lines at 7 minutes intervals throughout the day and there is one price for any distance you travel.