One part of this book where I went, "oh, wow," happens to be on the wikipedia page...so....
Bam. For those of you playing along at home, this happens from page 119-145.
Now, some parts of this are pretty easy... The blue box references how the word house is colored blue. It's a box because they're going down the crazy staircase. That's why the text is forwards on one side and backwards on the other.
However....what's up with the sidebars? The first time I read through this section, I kinda blew by them. Now that I'm thinking about it, though, they remind me of walls. So I started reading them...Googling the Pittsburgh name that popped up, I found this, which is interesting...no house. Just a bunch of other buildings. The entire left hand side is a big list of architect firms and buildings.
If we flip the book over entirely and read it the other way, the other sidebar is entirely the names of individual architects.
So we have walls built out of things and people who are made of and make walls. That's as close as I can come to an interpretation.
I'm imagining he's doing this because our adventurers are exploring completely unknown territory. It's trying to emulate the visuals, but with layout.
The smaller sideways blocks still escape me, though. I have no idea what's going on there.