Where to find old newspaper?

I just want to check back the old newspaper in past few yrs,
then where can I find them??
Dun tell to go on net!!

I've heard that it' ll be found in Public Library ,
but is that available in district library or specific library??

And how many yrs the old newspsper will be kept??

Last but not least, is there any museum in HK provide the service of
checking old newspaper??


Much Thanks!!