Mount Bukak and Seoul fortress
Seoul is wonderful and always-wake-up city but sometimes it is better to leave bustle of the city. Once I arrived to Seoul I was determined I must climb on one of these "fang" mountains. If you like hiking and nice views I recommend this trip as the number one what to do in Seoul.
One who visits Seoul I must admire the strategic location of the city. Downtown of Seoul lies between the river Han, Namsan Mountain and from the north it is protected by strip of mountains which are dominated by sharp Bukaksan. Whole city once used to be protected by fortress meandering over tops of these mountains. It not only gives the city "pretty" outlook (it feels almost like they built Paris in New York of Alps). In combination with view and the wall(Seoul) it also must have been great strategic place for city defense. Although the size is probably not comparable, the landscape, the mountain it all can remind you pictures of the Great Wall of China.
But these places don't belong just to past. Nowadays Korean army is using the advantage of the steep slopes of Mt. Bukak and built there a military base and loads of observation posts.
Fortunately Koreans are very liberal in this matter and (only recently) opened "Bukaksan" part of the wall to public. Due to the proximity to the base, it's not that free. To get inside of the area you must take your passport with you(no need for reservation as you can get confused by official website and other articles on blogs). At the entrance you will present your passport and they'll give you a number tag. In the area for obvious reasons it is forbidden to take pictures except one or two places. There is a camera every 10 meters and a soldier (although) in uniform every 20 meters. They are not dressed in uniform but once in a while there was a officer running around controlling if they stand properly.
To get there I recommend to take off at Hyehwa station (line #4) and use exit to take bus #08. The bus will take you up to the hill to the very steep streets of Seoul (I really couldn't believe the bus can make it). Get off the bus at the last stop (Jongjeom) and than continue walking to the hill. You will get to the wall and after just stick the wall. This path will lead you to Malbawi information center.
The wall in this part is truly amazing, preserved and it was really pity I couldn't take pictures. On the other hand the view to city itself is not as good as from the hill of Poet Yun Dong-Ju. For the best view(view from N-tower is boring comparing to this) I recommend not to end with leaving the forbidden area and continue the hike along the wall to this hill.
To add the entrance is free(amazing, isn't it?) and all that took me approximately 4 hours. The climb and descending the second hill is a bit more demanding so I would recommend better shoes than flip-flops.