The Cathedral of Brasília in the capital of the Federative Republic of Brazil, is an expression of the architect Oscar Niemeyer. This concrete-framed hyperboloid structure, seems with its glass roof reaching up, open, to the heavens. On 31 May 1970, the Cathedral’s structure was finished, and only the 70 m (229.66 ft) diameter of the circular area were visible. Niemeyer's project of Cathedral of Brasília is based in the hyperboloid of revolution which sections are asymmetric. The hyperboloid structure itself is a result of 16 identical assembled concrete columns. These columns, having hyperbolic section and weighing 90 t, represent two hands moving upwards to heaven. The Cathedral was dedicated on 31 May 1970.
How much does the glass weigh? (If the question is unanswerable, say "unanswerable")
unanswerable