In 538, King Seong moved the capital to Sabi (in modern-day Buyeo County). However, Gongju remained an important center until the kingdom's fall in 667.
The move was intended to reduce Seoul's overcrowding and economic dominance over the rest of South Korea; perhaps not coincidentally, it would have also moved the government and administration out of range of North Korean artillery fire.
The projected cost of the project ranged from $45bn to as much as $94bn.
The plan has aroused controversy, with opposition parties calling for a referendum to see whether it is endorsed by the population. Some civic groups have also launched a constitutional appeal, and on October 21, 2004, the Constitutional Court ruled that the special law for the relocation of the capital is unconstitutional since the relocation is a serious national matter requiring national referendum or revision of the constitution, thus effectively ending the dispute. Opinion polls showed that a slight majority of South Koreans are opposed to the move, both before and after the ruling.
However, late in 2004, the government announced yet another plan that will allow Seoul to be a capital in name only by retaining the Executive Branch in Seoul, while moving all other branches of government to Gongju. The question remains unresolved to date.
Gongju was a capital of Baekje, and was a provincial city governing Chungcheong provinice. So it has lots of good places to visit. King Muryeong's tomb is the most famous site to visit and Gongsan Castle was the remained site of Baekje's palaces. Gongju National Museum displays the treasures found in King Muryeong's tomb.