If you visit Seoul during the months of November or December, you have to read about the Lantern Festival in Seoul. Since its inception in 2009, the festival has achieved great popularity and there are amazing queues in the Cheonggyecheon stream in central Seoul. Amazing! Under the theme of "Seoul Ancient History", the Lantern Festival of 2011 I attended began with a lighting ceremony at the Plaza Cheonggye - very, very close. Then, during the festival period, hundreds of lamps, the stream still burning. I recommend doing it at night - take a quiet walk along the shore and watch the over 30,000 colored lights floating in the water and air. If I remember correctly, the walk could last almost a mile. In case you want more information, in 2011 the hours were from 17:00 to 23:00 every day. And of course, the entrance was free.