A map of the Pontine marshes


Leonardo da Vinci

Probably acquired by Charles II; Royal Collection by 1690


This map covers a stretch of about forty miles (65 km) of the coast south of Rome, with north to the upper left. It concentrates on the Pontine marshes, a malarial plain caused by the coastal dunes that prevented the many small rivers flowing from the Monti Lepini and Ausoni from draining into the sea. The 500m-high promontory of Monte Circeo is at lower centre, and the large town of Terracina is set among hills to the right. Running horizontally through the middle of the map is the Via Appia, the ancient road from Rome to Brindisi, begun in the fourth century BC. Leonardo has simplified and exaggerated the curves of the coastline, and there is an excessively abrupt transition from the flat marshes to the rather uniform hills. Although the drawing is by Leonardo, the inscriptions are in the hand of his pupil, Francesco Melzi.

Attempts to drain the marshes had been sporadically attempted since early Roman times. The river Ninfa (here labelled Nympha) was canalised alongside the Via Appia to attempt to control flooding of the road, and around 162 BC another channel, later known as the Rio Martino, was dug south-west from the Ninfa across the marshes direct to the sea. The territory was ceded by Charlemagne to the Papacy around 800 AD; after centuries of neglect, Popes Boniface VIII around 1300 and Eugenius IV around 1440 each attempted to drain the area around Sezze and Sermoneta, to the upper left of the map, but their modest gains were lost as soon as maintenance ceased and the channels silted up.

In 1514 Pope Leo X attempted to resume this work, but he was opposed by the Duke of Sermoneta who feared losing control over fishing rights in the marshy lakes. So instead the Pope entrusted his brother Giuliano de’ Medici, commander of the papal army and Leonardo’s main patron in Rome, with the task of draining the south-east of the region, towards Terracina. Giuliano went into partnership with a Messer Domenico de Juvenibus to further the project, and on 19 May 1515 a contract was drawn up with the engineer Fra Giovanni Scotti da Como to execute the scheme. As was usual with such schemes, the participants were to be rewarded with the gift of some of the reclaimed land. But the present map demonstrates that Leonardo too was involved in some capacity. A decade earlier he had made fine and accurate maps for Cesare Borgia (son of Pope Alexander VI and, in his own day, commander of the papal troops) and for the Florentine government, the latter in connection with hydroengineering schemes. It is highly unlikely that Leonardo surveyed such a large area as this himself: the map was presumably based on an earlier model, and it is possible that Leonardo did not himself actually visit the area and that his involvement in the project went no further than producing this map for his patron.

The scheme was simple, and is indicated with little fanfare on the map. First, to cut a channel flanking the Via Appia direct to the sea, thus draining the marshy waters that had built up behind the coastal dunes. This channel is visible as a single diagonal line at the centre right of the map, cutting through the meandering streams to the left of the word ‘badino’. And secondly, to excavate what remained of the ancient Rio Martino and to reconnect it with the Ninfa: the Rio Martino is the straight canal at the centre left of the map, and Leonardo’s (or Scotti’s) proposed new channel is the single line connecting the Rio Martino with the confluence of the Ninfa and other rivers at the Via Appia.

Digging of the first channel, later known as the Canale Giuliano or Portatore, began in 1515 and was immediately successful. But the citizens of Terracina soon began to resent what they saw as papal annexation of their territory, for although the marshes were a papal possession, for centuries they had been essentially common land. The deaths of Giuliano in 1516 (whereupon responsibility was handed over to his nephew Lorenzo) and of Leo X in 1521 saw work grind to a halt without any excavation of the Rio Martino. Over the next four centuries further sporadic attempts were made to drain the marshes, and it was not until the 1930s that the area was fully drained and malaria eradicated, though to this day the area requires continuous pumping.

Pen and ink, wash, blue bodycolour, touches of red chalk, over black chalk and stylus

27.7 x 40.0 cm

RL 12684