This is one of the best examples there are of the problem you will face: https://en.wikipedia.org/wiki/BBC_Domesday_Book
It might be better to ask how you can keep the data alive rather than in suspended animation. Assuming the Internet will still be around that long from now (either as we now know it or in some mutated/evolved form containing everything ...
You want a disk that will hold data for centuries?
OK, let me introduce M-DISC
Unlike other disks, M-DISC data can actually survive up to 1000 years. It looks almost the same as normal CD but it's more glossy.
I think generally you should avoid flash storage and magnetic storage devices, because the chips will loose their information over time (e.g. most EEPROMS keep their data for about 10 to 15 years). You got the same problem with magnetic storage devices (although I have some really old 5 1/4" floppies, which work fine until today).
I would go with an ...