Exchange or Octagonal Hall: Completes the ground floor of the Stock Exchange or the Octagonal Hall. It's originally purpose was for trading business. It is one of the most changed spaces from the 1950 restoration project. In the course of time it has returned to its original size. Intended for a commercial use as a space for the sale and trading agricultural products, grain in particular. Over time, the hall and the surrounding areas have hosted the smoking room and billiards. These items were deleted by Pisani renovation in 1950, that wanted to create a concert hall space and a work area for the Café.