First idea was a hyperbolic stadium with many lines, but it turns out that it is already built in Beijing, so belive it or not its not a copy, it is like brother of Beijing's national stadium.
I have used Rhinoceros, Grasshoper, V-ray for Rhino, SketchUp, Photoshop..
In project there is:
Top view, Front and back view, steps, and 3d model of a stadium.