Often, the program ends up amazing. You'll say, "This is beautifully architected." Well, where did that architecture come from?
In this case, architecture means the systematic way we deal with diverse requirements. Architecture allows us, when we go to do work we need to do on the program, to find where things go. It is a system that was worked into the program by all the little decisions we made — little decisions that were right, and little decisions that were wrong and corrected. In a sense we get the architecture without really trying. All the decisions in the context of the other decisions simply gel into an architecture.

A Conversation with Ward Cunningham (2003) - Working the Program