Every Tuesday and Thursday I find myself in the same lecture hall that I was in 45 years ago. Back then, it was a Botany course, and now it is "History of Science and Technology in Western Civilization." On those days I also have an earlier class in "Film in American Culture."
The deal at The University of Maryland is that a retired person over 60 may taken up to 9 credits with minimum tuition plus books and parking. I have chosen to audit rather than taking the courses for credit, so I won't be writing papers or taking exams.
Without the pressures I had as an undergrad, it's pure learning and it's great.