Most code is not worth reading. Even well structured codebases are mostly composed of code which is not worth reading.
The difference in a well structured codebase is that some of the code prevents you from having to read huge amounts of other code. All code is bad, it starts out bad just by existing, it's only redeeming quality is preventing you from having to deal with more bad code.
Everyone thinks they write good "clean" code, and it's never true. Good programmers are good because of the architecture of their code, not because a single excerpt of code in isolation looks a certain way.
What you really want to read about are good designs. Read APIs, models, concepts, schemas, etc.
Another comment mentioned the Go standard library, and I totally agree. But stop at the APIs, if you look inside, you'll see that it's also mostly garbage. It's good because the APIs are good, and you don't have to read the rest.
I don't know, I argue APIs and models are "code" in the informal sense. Architecture is important, but it's even harder to understand "good architecture" than code, not without the architect right there explaining it to you. Many decisions were made for some reason that you can only understand through experience.
There's definitely a code component to them, but most of reading about and understanding them would come from reading the surrounding documentation or reasoning. Most of that text would be prose, rather than a language consumed by any computer system.
I'm not sure what you mean by "understand good architecture." One thing that makes an architecture good is its simplicity and clarity. If it's hard to understand, it can't be that good. I can say for certain: if you understand the problem being solved but not the architecture, then it is for sure a bad architecture.
The difference in a well structured codebase is that some of the code prevents you from having to read huge amounts of other code. All code is bad, it starts out bad just by existing, it's only redeeming quality is preventing you from having to deal with more bad code.
Everyone thinks they write good "clean" code, and it's never true. Good programmers are good because of the architecture of their code, not because a single excerpt of code in isolation looks a certain way.
What you really want to read about are good designs. Read APIs, models, concepts, schemas, etc.
Another comment mentioned the Go standard library, and I totally agree. But stop at the APIs, if you look inside, you'll see that it's also mostly garbage. It's good because the APIs are good, and you don't have to read the rest.