Kamenose Landslide Museum of History
The 1932 Kamenose landslide, located on the border between Osaka and Nara prefectures, dammed up a river and crushed a railway tunnel. The tunnel, reinforced for modern-day standards, still exists for underground tours.
【official site】
https://www.mlit.go.jp/sogoseisaku/region/infratourism/en/infralist/osaka/index02.html