Locked In History at Seodaemun Prison, Seoul, Korea
It's not as good as Abashiri, but Seodaemun is a very well-done museum for those interested in dark tourism or history. Doors open at 9:30, closing at 18:00 (17:00 November-February). They're closed on Mondays and a few holidays. Admission is 3000 won ($3). Access is very easy; take Subway Line 3 to Dongnimmun Station and go out Exit 5 - the prison is right there. You'll need to go up the hill to get to the front gate seen in my first picture.