Things to do alone on birthday?

So my birthday is next week and I originally planned to celebrate with friends and family. Well, many people got Covid and while they’re doing well, it has resulted in me spending my birthday alone. I was wanting to do something cool in the city, and I was wondering what solo activities would be fun to do. (Without disclosing the day, it will be on a weekday).

EDIT: thank y’all so much for your suggestions! You guys are awesome and I now have a pretty cool day planned out! I appreciate y’all!