The model was made from the first complete design by Jacob van Campen, possibly in spring 1648. The scale is 1:45. The facades were built as shown in the model. However, the roof was lowered to the same height as the tympanum. In this way the lower part of the dome emerges free above the roof. Inside the model there are differences between the two sides of the building, allowing the architect the freedom to make changes during the course of construction. Thus one of the four main staircases only ascends to the second storey. The idea of this model was to help designer and architect to understand some of the problematic issues involved. The architect who carried out the building work was Daniël Stalpaert (1615-1676). One of the problems was how to get the maximum light flowing into the Burgerzaal (Civic Room).