I agree entirely with Cindy's interpretation of "in your face". However, I also think that the architect is saying that "we" (presumably he and his colleagues of 20 years ago) were trying to make a statement with their design. They wanted to declare, loudly and proudly, that they had somehow "arrived" in architecture, and the "in your face" design would be the way they were going to do it. The design may well have been quite radical for its day, and indeed, "in your face" might also mean they were thumbing their nose at the establishment a little, breaking the mould, doing something really different, that sort of thing.

Just some additional thoughts - not enough room to write all this in the little peer grade box!

be in your face (slang) = to be shocking and annoying in a way that is difficult to ignore eg dance music that is aggressive, sexy and in your face