"The choice of material was the easiest thing (in this project). There is nothing more suitable than titanium zinc sheet, not only in terms of technological possibilities for its processing and performance, but it (the sheet metal) also provided me with the color unity with the palace building and of Paribas Bank, which is in a common tonality. However, in this period, the roofs of such buildings were most often made of lead sheet, of slate plates, which are also dark gray, or of zinc sheet." Prof. D.Sc. arch. Zheko Tilev