I need to work harder at mapping out our code to understand it as you say. I keep telling myself every codebase is different and none are perfect, but it is so

I need to work harder at mapping out our code to understand it as you say. I keep telling myself every codebase is different and none are perfect, but it is so nice to work in fresh or at least clean code. My project is about 200KLOC C# 2.0; we have a single .cs file 13,000+ lines long and no, it's not generated. We have a single method 900+ lines long in our DAL containing 23 separate hand coded SQL queries and no, it is not a report. Our codebase contains exactly 14 unit tests. 10 of which were written by me. Your prayers are welcome.