500-m gallery is officially known as Sapporo Odori 500-m underground walkway gallery and is located between subway Odori station and Bus center mae station.
This gallery used to be temporary and it has become a permanent facility since 2011. This is the longest museum of museums in Japanese stations. Admission fee is free, of course.
Artworks made by artists in Portland are displayed currently. By the way, Portland in U.S. is the sister city of Sapporo. I saw the artworks a few days ago, but I was not so impressed so much. To be honest, I was much more surprised by the existence of this walkway. I didn’t know that I could go to Bus center mae station from Odori station by walking through the underground walkway! I didn’t know that for a long time!!