Kirk here. I haven't been able to post much about the castle so this article is welcome. It includes a YouTube video of a stone wall crumbling. That said, even though the Smithsonian is a reputable institution, I can't endorse the article without reservation. For one, the title is sensationalistic and oversimplifies what happened: "This 400-Year-Old Impenetrable Japanese Castle That Survived a Samurai Siege Just Crumbled in an Earthquake." No, the "castle" didn't just crumble. There are probably other issues that I haven't noticed yet but, even so, it has some good links to other material so I'd recommend checking it out if you are interested in the castle.