Confidence in an architecture

How do you get confidence in an architecture? Lot's of extensive verification?
(This raises the quesiton on how to verify an archtiecture when you have not yet built a system based on the archtiecture. More on this at a later time...)

I think that you get confidence in an architecture by throwing things at it when various stakeholders gets involved and see how well it can handle them (all prerequisistes are never known in the beginning).
If the architecture can absorb a particular issue, scenario or feature, without deviations from the fundamental cornerstones or adding extra elements each time, the architecture gets stronger for each thing you throw at it. And your confidence in the architecture increases.
On the other hand, if you need to modify the architecture for each thing you throw at it and after enough times it is not recognisable when compared to the initial draft the architecture gets weaker and after some time there is little confidence left. And you should re-evaluate if it is the right architecture.

An architect must be able to have this "outsider" perspective and kill his/her darlings when necessary.