I think the Cristo Redentor probably one of the most recognizable symbols of Brazil, and whether or not you are Christian it is pretty impressive feat. I am an atheist myself, but that doesn't preclude me from appreciating artistic/architectural achievements that represent religious symbology. Along with Taj Mahal (also pictured) it is one of the New Seven Wonders.

In your mind, what would be a better symbol? The National Congress is pretty recognizable but not nearly as iconic.