During an IT site visit at my workplace, I had to go into a well-hidden cellar. The person who let me in said he hadn’t been in for twenty years. I suspect not many other people have been in, either.
The cellar sprawled out under the foundations of a large building with interesting alcoves and side rooms. Several of the rooms contained ancient equipment to ventilate the building above, using dangerous-looking belt-driven fans to draw air in down a grille at street level and blow it into enormous ducts which disappeared off around the place. Thankfully the fans were not running, because their blades were not enclosed.
My favourite room was small, but very tall indeed. It had shelves from floor to ceiling, all creaking under the weight of bundles of old documents, wrapped up in brown paper and tied with twine. A few documents were lying around on the floor, so I had a look. There were exam papers dating back to the 1890s (older than the building), booklets of log tables, minutes from meetings that happened a century ago, and some classical music scores.
Apparently at some time in the past, someone had sorted through some of the documents and some of the bundles were labelled “KEEP” or “THROW”. Those labels were yellowed with age so I think the would-be organiser embarked on the tidying at least 30 years ago and never finished the job.