It's not even touching the techniques and approaches yet. I was too lazy.
Here a summary of my understanding: * Relentlessly hire the best, train them and give space for them to grow and shine. This is the basis. It's not that a less quality engineer cannot grow, it's just too costly to do that at large scale. * Build the infrastructure to support large scale engineering. The best example is the idea of "warehouse scale computer" that is the data center, embodied in systems like Borg Spanner etc. * Relentless consistency at global scale. Example would be the Google C++ style guide. It's opinionated at its time, but is crucial to ensure a large C++ code base to grow to big size. * Engineering oriented front line management. L6-L8 managers are mostly engineering focused. That's necessary. * Give the super star the super star treatment. Google's engineers are rewarded as strategic asset of the company. Numerous example are made public.