From what I discern from the OP, you do not have to actually take your investment with you.
For that reason I would say over a 100 year span, any “common” investment such as an index fund, deed to land or et cetera would work fine.
For 500 years, everything goes out the window.
Precious metals will always have some value, so they are probably the safest bet, and also they will be the easiest to convert back into 2500 AD currency than other investments.
Anything else is just such a huge gamble. Believe it or not there are very ancient artifacts that are not particularly valuable even to this day. You can buy genuine Roman coins for $100 or even less for some (and some cost hundreds of thousands, some of them we still have tons of and some are ultra rare–that’s the dig, there’s no way to know what will be ultra rare in AD 2500.)
Most works of art are the same way, any work of art you can afford right now for $100,000; may be of little interest 500 years from now or you may have bought from today’s equivalent of van Gogh, who is unknown in our era but is the most celebrated painter in history 500 years from now.
In value/pound, obviously works of art are a great value for this kind of venture but only if you are certain of how valuable they will be in the future. Any work of art that you can be certain will be valuable 500 years from now is probably very expensive now (meaning outside the $100,000 range.
I suppose working machines from our era would be very valuable in 2500 AD. I don’t know jack about storing something for 500 years in a manner that will keep it operable. Is it possible to, through some mechanism, store a modern day car, computer, DVD player, blender, or et cetera such that you can have a decent expectation it will still run in 2500?
I doubt rusted out cars from 2000 will be totally uncommon in 500 years, as artifacts, but a 2010 Camry that is in full working condition, with only original factory parts? There won’t be any of those 500 years from now.