Archive.org – the internet archive.
This is a great resource for seeing how far we have come or to bring back a website that has since been shut down. The Internet Archive has a great feature called the Wayback machine which allows you to look back on old versions of websites. See what google looked like back in 1999 or how IBM shouted out to the world in 1996. How far back can you go? What is the oldest website you can see?