One of the very first projects in my career was php (plain php, no frameworks, no js) cms system for medical facilities. By that time, I didn't know how web works (I mean, I knew even less than now) and my coding skills were very rough. I have spent 3 years in support and happily left the company in early 2013. And today I have found, that this project is still alive, used and they haven't changed admin password 🤪
Somewhere in this site there are my own implementation of mvc and orm.. even before I knew about these pattern or read GoF book.
This has the shittiest code, that I have ever wrote for production and I think, by far the oldest that is still in use.