Construction of the two storey station (there’s also a floor below ground too) designed by Tsukamoto Yasushi of Tokyo Imperial University began in 1922 of mixed stone and brick and was finally completed in 1925. It was originally known as the Keijo Station Building and renamed Seoul Station in 1947.
The pictures here show the station as it would have originally appeared although later northern and southern terminals were added in the 1960s to allow for additional capacity. This is apparently the oldest surviving railway station in Korea.
Before this building there had been a previous station which opened in 1900 as Gyeongseong Station and was renamed Namdaemun Station in 1905, due to its proximity to the Namdaemun Gate.
There is a small museum and gallery attached but both it and the rest of the building was closed last weekend when I visited for what appears to be a general tarting up.
A Few Random Posts on Seoul I - The Dongdaemun Gate