During our trips metro is always the most preferred means of transport for us. Before we choose a hotel we check if it is close to the metro station. As a rule metro can save much time and is the most convenient way to travel within a city. We used metro in various cities like Milan, Rome and Prague. But to my mind Barcelona metro is of a higher level of quality.
Barcelona metro is amazingly convenient, simple and clean. It works from early morning till midnight. During our week-long stay in Barcelona the subway cars were always half-empty and it was only once when we were caught in the crowd.
Today the metro network consists of 9 lines (including 4 suburban lines) numbered L1, L2 etc. and they are distinguished on network maps by different colors: red, green, yellow, blue and violet.
On a single travel card that is valid for 45 minutes and costs 1.95 euro you can use different modes of transport. But if you are going to stay in Barcelona for a few days it is preferable to buy a card that includes ten rides at a discounted price.