Testo originale - Inglese - The retractable inner roof is located entirely...

The retractable inner roof is located entirely within the "hub". The upper and lower tension rings serve as "rims" for two further "spoked wheels" systems meeting at a single common hub above the centre of the bullring. The retractable membrane is draped over the lower cables of this inner system. When the roof open, it hangs bunched up in the centre. When the roof is to be closed, 16 small electric motors draw the bottom edge of the membrane out to the lower rim to form a circulair tent.