"Invincible Sitewide Pages" ?

Hi.

So.

What I want/need to do may seem strange:

I want to have some pages that are sitewide and non-deletable.

Basically, I'm creating CMS sites for a chain/franchise organization, and I need certain key pages to ALWAYS be there. Like a calendar page, and some special archive-like pages.

But the users also need to be able to create, edit, and delete pages of their own.

So what I need is "Invincible Sitewide Special-Function" pages to co-exist peaceably alongside user-generated pages.

The reason is that I don't want users to be able to delete important pages.

How might I go about this?

Thanks,