Here, then is a list of places where you may enjoy the fall foliage. ( not in any order of preference):
1. Gyeongbokgung - Leaves on the palace grounds are expected to peak around early November. According to the Cultural Heritage Administration. "early to mid November will be the best time to enjoy fall foliage at the royal palaces in downtown Seoul....Leaves will begin to turn about ten days later than normal this year. It ....expects the scenery to be better than normal as a result of wide differences in daily temperatures."
2. Changdeokgung
( Exit 3, Anguk Station, Line 3) "A UNESCO World Heritage site, this Joseon-era palace includes many serene gardens. One of Changdeokgung's gardens houses over a hundred varieties of trees. However, in order to appreciate the foliage of the Changdeokgung gardens trees, visitors must join a guided tour or pay a hefty 15,000 won for an all-day self-guided tour only available on Thursdays."
3. Changgyeonggung
4. Deoksugung - It is also open at night but do check out in the daytime Deoksugung Stone Wall ( Exit 3 or 12, Deoksugung Station, Line 1 or 2). Fans of the TV drama series, Lovers in Prague, may recall a romantic scene shot here.
5. Samcheongdong Road, a.k.a. Gallery Road, which starts at the south east corner of Gyeongbokgung, is lined with gingko trees. You can also explore the beautiful grounds on Samcheonggak.
6. Namsan - I'd suggest you walk up to the top and then take the cable car down. That way, you can also enjoy the 'chak-chak' of the local magpies. (Their size was also surprising.)
7. Bugaksan - Actually I think I enjoyed the views of the Seoul suburbs from Bugaksan more than from the vantage point of Namsan Tower. Probably because it was more hard-earned as the climb up Bugaksan seemed to be harder-going. Don't take my subjective word for it.
8. Jongmyo Shrine
If your timing is right, you'll also get to witness a Confucian ritual held here in grand style.
9. Sowolgil
"Running south of Mt. Namsan for almost 4km, this ginkgo-lined boulevard (best approached via Exit 1, Myeongdong Station, Line 4) offers plentiful space for rest and quiet contemplation. Sowolgil in fall looks like a scene from a film, with bright leaves scattered artfully across the walkway. The pathway eventually connects to Namsan Park." You may want to check if the bicycle elevator that is supposed to be built on this road has been completed. What does a bicycle elevator look like?
10. Hongneung Arboretum
" Seoul's only arboretum, Hongneung Arboretum (approached via Hoegi Station, Line 1 or Exit 3, Korea University Station, Line 6) is made up of nine gardens, including an aquatic garden, a wetland garden, a coniferous tree garden, and a garden of edible and medicinal plants. The garden of broadleaf trees, located behind the main building, is stunning in fall when hundreds of trees transform into a vivid array of bold colors. A tour of the entire arboretum ─ approximately 780 square meters in area ─ takes nearly three hours and is free of charge."
sources:
http://world.kbs.co.kr/english/news/news_Dm_detail.htm?No=76485&id=Dm
http://english.chosun.com/site/data/html_dir/2010/10/28/2010102800984.html
http://english.visitkorea.or.kr/enu/SI/SI_EN_3_6.jsp?cid=1104134
http://english.visitkorea.or.kr/enu/SI/SI_EN_3_1_1_1.jsp?cid=264337
http://english.visitkorea.or.kr/enu/SI/SI_EN_3_1_1_1.jsp?cid=264348
http://english.visitkorea.or.kr/enu/SI/SI_EN_3_1_1_1.jsp?cid=264316
http://english.visitkorea.or.kr/enu/SI/SI_EN_3_1_1_1.jsp?cid=264350
http://english.visitkorea.or.kr/enu/SI/SI_EN_3_6.jsp?cid=261031
http://www.korea.net/detail.do?guid=46128
http://www.klm.com/destinationguide/gb_en/airline-ticket/asia/east-asia/south-korea/seoul/thingstodo.htm
http://www.visitkorea.or.kr/enu/SI/SI_EN_3_1_1_1.jsp?cid=264314












