Archive mind

This isn't really a very Fridayish post, and as I'm going offline for the weekend in about 10 minutes (we're still internetless at home) it's going to look like a bit of a drop-it-and-run thing; but for anybody with any kind of interest in the web, a question:

You need to 'archive' some of the regularly updated bits of information which are published on various areas of your website for up to two years (no, really, you do, whether you like it or not). Your users need to be able to access the archived stuff in the same way that they can access any other bit of the website, but they probably won't actually look at it all that often, because they'll be more interested in the shiny new stuff. The info will all be backed up and archived off the web anyway, wherever (or indeed whether) you put it on the web, but you have to put it on the web and make it available to your users because that's what the nice people who give you money have asked for. 8-)

Do you

a) have a separate 'archive' section where archived material is stored, whether with this section
i) mirroring the structure of the main/current website or
ii) being organised in some way more suitable to the archive; or

b) just have a de facto 'archive' where each relevant area has the most current addition/version/whatever but also all the necessary back issues/versions/whatevers, i.e. your 'archive' material is not stored separately but integrated into the main site structure...?

I can think of various pros and cons for both (from both user and site-maintainer POV), but I want to avoid prejudicing my readers' decisions.

BTW, this is a purely hypothetical, abstract, academic question about some interesting information management issues, and not a "do my homework research before Monday's meeting" kind of question at all, oh no.

TIA as always for your input...

NB edited to add a bit about access/backups above