I just boosted a post from the Astronomy Picture of the day, which is a site that has been going strong since June 16, 1995.
It's one of the first sites that I thought was really cool, and for many years it was the site I saw when I opened my browser every day.
Their archives go back to their very first post, which back then was HTML 1.0 . And I love the fact that even their modern posts LOOK like they could be HTML 1.0, even though they're not.