I've always loved old brick/masonry high schools. The kind that the main character in a 90's/early 00's sitcom would go to, but you never knew anyone growing up who actually went to a school like that.
Some of my favourites I've come across on Google Maps binges:
Duluth Historic Central High School
This one stood out to me because of the striking resemblance to the old Toronto City Hall. the architecture is much more reminiscent of what you see in the commonwealth countries compared to pre-war Rust Belt cities.
El Paso High School
The most Texas design ever, where the entire school sits perched atop the football field, and the back steps basically turn into the stadium seating.
Little Rock Central High School