iSchool at Illinois 130th Anniversary Logo
This logo is a great example of the fact that not all designs have to be a...well...logo. If you want to celebrate your anniversary but don't have a logo of your own to build on, you can do what this organization did and just create a simple graphic with words to describe your group. In this case, a large number 130 with arcing lines above and the name of their school below. Simple and effective, even if it may not exactly be a logo.
Source:
https://ischool.illinois.edu/news-events/events/2023/06/25/ischools-130th-anniversary-celebration