Photos of Seoul (Namdaemun, Dongdaemun and Myeungdong areas) plus lots of streetfood :-) With over ten million people, Seoul is South Korea's largest city and one of the largest cities in the world by population. Covering an area of only 605 square kilometres, smaller than New York City or Tokyo, it is one of the world's most densely populated major cities. The history of Seoul can be traced back as far as 18 BCE, when it was established as a settlement in Baekje. It's believed that the Wiryeseong site is in the boundaries of modern day Seoul. It has thereafter been the capital of the Joseon Dynasty.