Jeff Huang has some ideas on how to set up a website that is designed to last:

So my proposal is seven unconventional guidelines in how we handle websites designed to be informative, to make them easy to maintain and preserve. The guiding intention is that the maintainer will try to keep the website up for at least 10 years, maybe even 20 or 30 years. These are not controversial views necessarily, but are aspirations that are not mainstream—a manifesto for a long-lasting website.

Read his proposal to learn what the seven guidelines are.