Establishing the dimensions of the previously discussed fountain would basically have been impossible if it were not for the meticulous Master Jacopo della Porta and his interesting masonry and chisel work measurements. He carefully detailed that the basin was exactly 13.5 meters lion and one side was 8.33 meters wide, the other side being 8.77 meters. The fountain could be reached by a ramp of wide and shallow steps that descend from the surface of the piazza.
We have made mention of Jacopo della Porta in connection to this fountain earlier. When the Congregation of the Fountains decided to build a large number of fountains that would be supplied by the Aqua Vergine. It was only a little while later that Sixtus V and the city authorities ordered for water fountains to be built using the Aqua Felice, and della Porta was also the architect who provided the designs. From the Capitoline records it becomes clear that he was involved in the construction of fountains much earlier than this, at barely 26 years. It was through his activity working on the fountain that earned him the title of “Architect of the Fountains of the Roman People”. It is safe to say that his work on the Trevi Fountain was what caused his lifelong journey of creating water fountains.
It is strange that with all the focus on creating and building fountains by the Papal Council and the Capitol, none of the documentation of the fountains, even those of rather substantial importance, make any mention of plans for a more elaborate or exciting water feature in the place of the ancient one. The only document is the one mentioning the restoration in 1563. There is however, one plan for the actual fountain that does exist.
A selection of “architectural plans of public fountains by early masters” was published by Egger in 1910. This was one of the most important collections and archives which belonged to Vienna. There was an interesting watercolor in table 19 of the fountain, which may have never been published before, because it was never given a moment’s notice before this.
