To fully comprehend what a mammoth and expensive effort it was to resurrect Seoul’s long-covered-over Cheong-gye-cheon, pay a visit to this well-designed museum about the stream. It’s a good starting point for a walk along the riverside park. Across from here is the Cardboard House museum , a wooden shack that was typical of the slum houses that used to line the river back in the 1950s. It displays paraphernalia of Seoul dating from this period of time.