Personal highlights

1. Seoul Metro: 22 lines over a total of 1,100 kilometres!
2. Subway: one of the world's longest and best metro system
3. Bomb shelter: very deep stations to protect the people
4. My trips: regularly using the metro to move around Seoul
5. My experience: very convenient and easy to understand

Image sources

1. Traditional decoration
2. Escalator going down
3. Coming back up
4. Train from the airport
5. Me in a crowded train