Ask HN: What are examples of well architected software systems?

AWS has been promoting the idea of "well-architected frameworks" with example solutions at https://aws.amazon.com/solutions/implementations/

If we would bring this idea to traditional software systems, what would be good examples of well-architected software systems of existing open-source projects?

Let's take https://martinfowler.com/architecture/ as a list of architecture styles, I think Kubernetes (https://github.com/kubernetes/kubernetes) is a good example of well-architected microservices.

What do you think? Do you know other good examples?