A visit to Seoul would not be complete without mentioning the Seoul Subway system. It is the most extensive subway system in the world and has over 600 metro stations so you can use it to get anywhere in the city. It is simply the best and most efficient metro system we have ever used. The subway system is almost like another city underneath Seoul with many shops and restaurants located within the stations themselves. At times, it seemed like half of the people in Seoul were in the subway system at once, but the trains were always on time. We never had to wait very long for the next train to come along. I wish the DC metro system was this good.