PL/I was the software-engineering language in my undergraduate computer science classes also, although it was beginning to be displaced by Pascal in the introductory courses, and C/C++ in the advanced courses. (Mid-1980s, in case that is not already clear.) It hung on because, we were told, it was still in demand in industry, particularly at telephone companies.

I did a group project with it, and the language was large enough that we found that each member of the group seemed to have learned a slightly different subset of it.

PL/1 was the systems programming language for Multics. Certainly not a bad language to work with.