Yeouido is a large island on the Han River in Seoul, South Korea. It is Seoul's main finance and investment banking district. It is 8.4 square kilometres (3.2 sq mi) large and has a population of 32,674 as of August 2023.

Seoul, officially Seoul Special City, is the capital of the Republic of Korea (ROK), commonly known as South Korea, and the country's most extensive urban center. The broader Seoul Capital Area, encompassing Gyeonggi province and Incheon metropolitan city, emerged as the world's fourth largest metropolitan economy in 2014, trailing only Tokyo, New York City, and Los Angeles, hosting more than half of South Korea's population. Although Seoul's population peaked at slightly over 10 million, it has gradually decreased since 2014, standing at approximately 9.97 million residents as of 2020. Seoul is the seat of the South Korean government.