When I was just starting as a developer, I had to maintain an old system. I didn't know much so I assumed, all it's problems stemmed from my missing understand

When I was just starting as a developer, I had to maintain an old system. I didn't know much so I assumed, all it's problems stemmed from my missing understanding of the system. After working on it for a few years, I came to the conclusion that this wasn't the case. The system was inherently broken and not doing a rewrite would be negligence. I did a rewrite in the end, but I did it incrementally. Build a new API, and replaced parts of the interface with new implementations that used the new API. Took a year, but it was worth it.