What do to with old Data

So my Company has been around for about 20 years recently there was significant funds spent on the IT enviroment, one of the problems we face is what to do with old data especially in our finance department, old finacial year records etc, documents and files we dont use on a daily basis but cannot be deleted due to “we may need them one day” so what do i do? let it clog up my server? re-implement a recently retired server and move all the data there? SAN?

I dont want my nice new infrastructer full of old data but at the same time need it close by..