Explore Gwangjang Market and Insadong
Two places that I recommend foreigners visit, which are both in Seoul, are Gwangjang Market (광장시장) and Insadong (인사동).
Gwangjang Market is Korea's first official outdoor marketplace, and has been around for generations selling unique food, clothing, and fabric.
Insadong is a modern marketplace, and is probably the best place that you can find souvenirs to bring back home from Korea.
Check out the video below to learn more!