Friedensreich Hundertwasser

Built between 1983 and 1986, it is among Vienna’s most visited buildings and is one of a number of Hundertwasser’s original and disorderly works here and elsewhere in Europe that reflect his rejection of straight lines (“an uneven floor is a melody to the feet”) and rigidity, which he believed was fundamentally alien to “humanity, life and the whole of creation”.

I would like to know what he built with the brown stair.