You can download it from the link below.
You can also see how it looks using the 2.1 demo site. If it does not show automatically for you just use the "Theme Select" block at the top left and change it to the theme of your choice:
Newsgroups is what started it all off. These were the first forums around. They were not pretty to look at but they got the job done. These go as far back as the 70's. Yup, forums have been around a very long time. Most of them at the start were not for the public but for corporations and such and were held on an intranet, not the internet.