This is a very precious document, currently preserved at Palazzo della Bonificazione Pontina, located in Piazza Santa Domitilla (Terracina Old Town).
The detail reproduced in the image above is taken from the Memories by Gaetano Rappini (Bologna, 1734 – 1796).
He was considered the best hydraulic engineer in Bologna (one of the most important works was the channelling of Comacchio). In 1775 the new pope, Pius VI, called him to Rome in order to study a draining project for the Pontine Marshes. The area, in fact, was unhealthy, due to malaria and was intended exclusively for the breeding of buffaloes and fishing.
Rappini planned to solve part of the problem through the excavation of a large collector, called Linea Pia, parallel to the Appian Way and intended to convey to the sea, near Terracina, the contribution of numerous channels connected to it, in order to reduce the swampy waters.
In a detailed report of June 25, 1777 (now preserved in the State Archives of Latina), Rappini illustrated his project to the pontiff. He quantified the problem of the marshes: these occupied an area of 180,000 square miles. He also provided explanation about the swampy waters and how to dry up the land. The project was approved.
The document consists of 42 pages, with a general map of the Agro Pontino, divided by sections, and with a second color map, designed by Giambattista Ghigi. Recently it has been reproduced in a specimen. Rappini was appointed director of the works.
On April 5, 1780 Pope Pius VI came to visit Terracina (he had already visited it three years earlier), to realize the progress of the works. A third visit was made in 1789. The entire work, which employed up to 3,500 workers, reduced the marshy area: 29,000 hectares (71,660 acres) were drained; part of the swamps thus changed to cultivable land. At the end of the works, the division of the farms was carried out. Engineer Rappini obtained almost 2,000 hectares (4,942 acres). The total cost for the Apostolic Chamber was one and a half million crowns.
Near the ancient Appian Way, a new road was built from Velletri to Terracina, thus shortening the distance between Rome and Naples with an easy piedmont communication, instead of the old road traced on the heights, between Sezze and Priverno.
The text on the top says: “This collection contains copies of acts and agreements about in the solemn visit of 1777, about the division of borders, and remunerations related to the draining of the Pontine Marshes, with certain other acts and ancient documents about the same Pontine Marshes, and finally the deputations of the Draining Commissioners. All identified in the following Index”.
There is a concise chronicle of these acts, starting from March 21, 1586.