Try the following tour, recommended by residents or metro enthusiasts:
In addition to the different subway systems in Seoul, make sure to take a look at the Incheon subway, the Incheon Airport Maglev, and the automated LRT systems in the adjacent cities of Ujeongbu (a VAL line) and Yongin (identical to the Vancouver SkyTrain).
Gyeonggi Railroad Museum. The museum, as the name suggests, is about artifacts and vehicles from the over 100 years of railroad history in Korea from steam engines to high-speed trains. It was founded by Korail. The museum also exhibits subway and commuter trains. Indoors 2,900, outdoors 1,900 square meters. Since 1997. Address: 142 Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do. At Uiwang (Line 1) metro station. Hours (check before visiting): April to October: 09:00-18:00. November to February: 09:00-17:00. Admission closes 1 hour earlier. Admission: 2000 won. Features: Gift store, lecture room, nursing room. Reference: railroadmuseum.co.kr, info.korail.com (official website). visitkorea.or.kr, rachelkso.blogspot.de.
Some trains have buzzing noises (completely different than Paris) that sound like "le-le-le-le-le-le-le-le-le-le" until the doors close. Some just have a conductor standing outside and the conductor closes the doors when nobody in in the way. Next-station announcements in Korean and English.