More relevant to the HN crowd, he invented the general concept of a "pattern language" and described a set of patterns for architecture.

The Gang of Four took that concept, hunted down a set of patterns they found in software architecture, and wrote "Design Patterns: Elements of Reusable Object-Oriented Software" based on it, one of the most famous books in programming.

I’m neither an architect nor a software engineer, but every six months or so I flip through A Pattern Language just to help imagine buildings I’ve never been in. It’s a beautiful book.

I don't remember where I read it (sorry), but I recall that "The Timeless Way of Building" and "A Pattern Language" were supposed to be, or were conceived as, one book. But it would've been way too long, so it was split up. Generally, I think you're right: "TTWoB" is sort of the set up to "APL", motivating why "APL" is useful, and telling you how to use it. I remember I used to be more drawn to "APL" because you can just open it up anywhere, and since the patterns are so short, you just read a little bit and get inspired. It's bite-sized fun! But when I finally read "The Timeless Way of Building", things really clicked. "APL" is really illuminated by digesting "TTWoB" first. (I also think "APL" is more useful read cover to cover, though nothing wrong with taking some bite-sized inspiration once in a while :) )

So, I guess, besides just agreeing with you, sort of also saying, keep reading "TTWoB", soak it up, then you'll be primed for "APL". It's such a fun journey! (If you can't tell, I'm a big admirer of Christopher Alexander :) )

Another reading suggestion along those lines is "The design of design" by Fred Brooks (of Mythical Man Month fame). He discusses design approaches as uses his process of building his own house as the primary example:

https://www.amazon.com/Design-Essays-Computer-Scientist/dp/0...