Today is Hangeul Day, and it's being celebrated in various ways. Google has altered its insignia to incorporate Hangeul (a more pleasant unloading of han onto Google than complaints about the naming of the East Sea and Dokdo on Google Maps):
The National Korean Language Institute is in Banghwa-dong, and offers this banner:
Even the US embassy is celebrating the day.
Naver tells us that this is the 564th Hangeul Day, though according to Wikipedia it started in 1945 (which makes little sense, as there was no Korean government until 1948). It also mentions that North Korea celebrates it in January.