Just use a regular spinning hard drive, not any kind of solid state media. Solid state media must be charged and accessed periodically to retain its contents, like RAM, but billions of times slower.
Spinning hard disks use aluminum platters coated in an extremely purified layer of iron oxide (rust) all of which is super chemically stable. Once written your data will remain stable for hundreds of years until it is slowly ripped off the disk over time by gravity.
These drive are mechanical and the mechanics will fail far earlier so the data will need to be extracted from the disk directly by some invasive means. People already do this now to extract valuable data from damaged disks.
Regular hard drives are storing data through magnetic voodoo. Which means they will lose charge and thus data over time. And time here is measured in decades, not centuries. In fact, regular hard drives are even worse than SSD. Though, it all depends on the specific devices, how you store and handle them. There are also dedicated archive-HDDs, which are supposed to hold a bit longer than normal HDDs, but even they only promise decades. In general, for Anything longer than 50 years, don't even think about HDDs and SSDs.
Spinning hard disks use aluminum platters coated in an extremely purified layer of iron oxide (rust) all of which is super chemically stable. Once written your data will remain stable for hundreds of years until it is slowly ripped off the disk over time by gravity.
These drive are mechanical and the mechanics will fail far earlier so the data will need to be extracted from the disk directly by some invasive means. People already do this now to extract valuable data from damaged disks.