These two pictures came from the Korea National Records Service... showing the CBD of Seoul on April 1971.
The first one shows the overpass on Cheonggyecheon that removed in 2003 and the other Jeongdong area.

http://img340.imageshack.us/img340/4135/19712dw3.jpg

http://img340.imageshack.us/img340/4448/19713il0.jpg



April 12 1971... The construction of Seoul's first subway Jongno Line(today's Line 1) length 9.54km was started.
These pics show the scene of ground breaking ceremony and construction.

http://img511.imageshack.us/img511/6372/b1os7.jpg

http://img519.imageshack.us/img519/4683/b2rc6.jpg

http://img519.imageshack.us/img519/4194/b3de8.jpg

http://img511.imageshack.us/img511/7183/b5ub9.jpg

http://img511.imageshack.us/img511/4219/b4qw6.jpg



Jongno Line was completed on August 15 1974.
President Park Jung Hee could not attend this historic event... of course I know the reason why... :ohno:

http://img86.imageshack.us/img86/8571/c2yp2.jpg

Here is a 1985's Seoul subway map.
http://img102.imageshack.us/img102/4995/subway1985hs7.jpg



And 2006's... a bit different from today's line.
http://img180.imageshack.us/img180/1680/subway2006lz0.jpg



This map includes all of the lines under construction or proposed in Seoul Metro Area.
It will be nearly come true by 2020s if the plans are carried out smoothly... :yes:
http://img178.imageshack.us/img178/455/subway2020yp7.gif