Yi Sun-Shin Plaza (이순신광장). A college football pep-rally it probably won't be, but I can count the number of times I've seen a marching band in Korea on my elbow. Little background information is available, though one photographer wrote of last year's international version:
This festival is part of the celebrations for the 60th Anniversary of the Recapture of Seoul held from the 25 September to 6th October. The Republic of Korea requested musical support from several countries to assist in the celebrations[.]It's a recent addition to my list of Jeollanam-do festivals held throughout the year, now at over 110.
On the topic of uncommonly-heard musical styles in Jeollanam-do, the Gwangju Berner Oberland Yodel Club (광주오버란드요델클럽) has several performances scheduled in October.