sculpture
They wanted a monument
One of the responsibilities for an architect is to provide a space that is usable and enhances the possibilities for what you do. But mostly, museums are just the opposite; they're horrible spaces, anti-art, they can't be used. They can't function, they overwhelm it. So in a way, they become objects in themselves many times, almost sculptures, and they get a lot of aggrandizement out of it...In terms of Bilbao, the one difference there is that they did not really want a museum, they wanted a monument. They wanted a thing that would bring people to the Bilbao.
Strength from both mass and form
Hoover Dam has the shape of an arch dam, but it is actually a hybrid structure, gathering strength from both mass and form. The dam is often ranked as one of the most exquisite of all engineered structures. It is fitted to its site so well that the gnarly canyon wall looks like an organic growth engulfing the mass of concrete.