Answer :
The Imperial Post Office Savings Bank in Vienna was designed by Otto Wagner, who is known for his innovative use of "Modern Industrial" materials in architecture. One of the materials he used in this building is **aluminum**.
Aluminum was a groundbreaking material at the time of the building's construction due to its lightness, durability, and flexibility, allowing for unique and modern design possibilities.
Another material commonly associated with "Modern Industrial" architecture is **steel**, which was also utilized in many of Otto Wagner's designs, showcasing the shift towards using metal in construction during the modernist movement.
In summary, Otto Wagner incorporated aluminum and steel, among other materials, in his design of the Imperial Post Office Savings Bank in Vienna, highlighting his forward-thinking approach to architecture during that period.
