The tomb of King Muryeong, the 25th Baekje king, was discovered – miraculously intact and completely by accident – in 1971. The tomb and the six others in the vicinity aren't open to the public. Instead, an on-site museum has models of two of them that you can enter, as well as English-language information about the history of the Baekje kingdom. The museum is a 20-minute walk from the stone arch in front of Gongsan-seong.
At the entrance to the site, the Ungjin Baekje Historical Museum has more historical info and a tourist information centre. To see the actual artefacts recovered from the tombs, visit the Gongju National Museum.