One of the recurring themes in Leopold Mozart's letters, a theme that made him reflect not only on differences between Salzburg and the world at large but also how he might himself be an agent of modernity, isengineering, especially as it related to urban geography. In a letter of 8 December 1763 from Paris he wrote to Johann Lorenz Hagenauer how struck he was that the city had no walls. So when, in 1766, it was decided to cut a tunnel through the Salzburg Mönchsberg that would ease access in and out of the city, Leopold put forward his own ideas, ideas clearly influenced by what he had observed while on tour:
- According to the description I had, the entrance to the new gate from the town cannot be big because the entire wall in the fountain square, on which the horses are painted, is left standing. I imagine something entirely different: namely, I picture to myself that the entire wall is removed and the gate constructed in such a way that when one enters the city, the fountain is directly in front of him and he goes arount it, left or right. This seems to me freer, more open, easier to navigate, more attractive and more impressive.
A slightly later painting shows that the original design – not Leopold’s inventive re-imagining based on his experience of urban architecture in Paris – was the one adopted.