Nuova Pianta di Roma Data in Luce da Giambattista Nolli l’Anno MDCCXLVIII

Allan Ceen
Department of Architecture, Pennsylvania State University
Posted: April 15, 2005

Letarouilly’s 1841 Plan of Rome

Maps of the city of Rome may be divided into two distinct groups: those preceding Nolli’s 1748 Grande Pianta, and those following it. The second group follows Nolli in more than one sense: chronologically and graphically. Most of the maps between 1748 and 1870 either simply trace the Nolli map or use it as a base. Some cartographers, like John Roque who copied the small Nolli plan in 1750, acknowledge their debt. Others, like Paul Letarouilly who copied the Grande Pianta almost exactly in 1841, give Nolli no credit at all. The influence of the Nolli map persisted well into the 20th century. The government used it as the base for maps of the city until the 1970s. Architects still point to the map as the ideal figure-ground image for urban representation.

Before Nolli, the favorite way of representing the city was the view-map (bird’s eye view), as opposed to the plan-map (ichnographic or orthogonal view). From 1400 to 1748, there are only five plan-maps of Rome and two of these are minor. The three important ones are Bufalini 1551, De Rossi 1668, and Barbey 1697. None of these approach the accuracy and completeness of the Grande Pianta. After 1748, the majority of maps are plan-maps, especially in the 19th and 20th centuries. Tourists and pilgrims tend not to favor plan-maps, so for them a hybrid of the plan-map and view-map is most commonly available. This is a plan with the major monuments shown in three dimensional images, often misleadingly oriented. This type harks back to the Cruyl map of 1665.

Bufalini’s 1551 Plan of Rome

The Grande Pianta was published in twelve large (80 x 54 cm) sheets together with five sheets of indices and two smaller maps on single sheets. One of the latter is a reduction of the Grande Pianta, while the other, drawn to about the same scale, is Nolli’s careful reproduction of Bufalini’s 1551 plan of Rome. In the title Nolli acknowledges his debt to Bufalini as his principal predecessor. At the same time, his reorientation of the plan from East to North, and his use of the same graphic convention of shading for the inhabited area used in both this own plans, invites the viewer to compare the Nolli/Bufalini map to the small Nolli, and to draw the obvious conclusion that the latter is the better of the two.

Indeed, Bufalini’s 1551 map is very inaccurate in terms of distances and angles, but we must recall that it is the first plan of the city since antiquity, showing every street and city block, every church and major palazzo. As happened later with Nolli, it became the base map for many of his successors' efforts. This is dramatically shown by the fact that in the first half of the 16th century there are no maps of the contemporary city, while within 50 years after Bufalini, 20 maps of Rome are printed, most of which reveal their dependence upon his map by repeating the same inaccuracies.

In like manner Nolli’s Grande Pianta was a watershed for the cartography of the city. Nolli was the first map-maker of Rome to orient his map with North at the top (instead of the usual East), and to rely heavily on the magnetic compass for obtaining bearings on specific reference points in the city. The compass appears three times on his Grande Pianta: once at the bottom of the map as an actual compass being consulted by two putti, and once as a compass rose placed in the open space in front of S. Giovanni in Laterano (NN 5). On the latter, true North (T for Tramontana) is clearly distinguished from magnetic North (represented by the thin vertical arrow) on which the map is oriented. The surveyor’s Plane Table being used by the putto (lower right on the map), was also equipped with a magnetic compass so that for every position in the city to which it was moved, it could be always oriented the same way: North-South (Ceen 1991, pp.5-6).

As his principal North-South reference line Nolli used the sun-dial of S. Maria degli Angeli (in the Baths of Diocletian (NN 203)), which he refers to a as the "meridiana della Certosa" in his original drawing (Frutaz 1962). This accurate North-South line, inlaid in brass in the marble floor of the church, was set up in 1702 by Francesco Bianchini for the purpose of precisely determining the equinoxes used for fixing the feast-days of the Catholic Church. Aware of the 13° difference between true North and magnetic North, Nolli was able to make all his sightings refer back to this base line, or to parallels of it placed on other parts of his drawing. This technique, coupled with the triangulation of prominent city features such as towers and domes, enabled Nolli to obtain the accuracy for which his plan is famous.

The accuracy of the Grande Pianta far exceeds that of earlier maps of the city, and has not been significantly improved upon since its publication. But if accuracy were its only attribute, this map would be unremarkable among a number of others. What really makes it stand out is the wealth of detailed information to be found on its twelve sheets. No other map of the city approaches the Grande Pianta in this respect. A few specific examples will suffice to make this point about the map’s fine details:

a) the presence of the small corner fountain (of the bees) at the corner of Via Sistina and Piazza Barberini (now moved to the Via Veneto corner) b) the presence of two elevated galleries connecting the two halves of the Carceri Nuove (NN 662) c) the presence of four tiny dots in Piazza S. Pietro which are the centers of arcs of circles for the oval defining the plan of the colonnades

On a larger scale, Nolli records otherwise unnoticeable asymmetry in the Spanish steps and Piazza del Campidoglio. But perhaps Nolli’s greatest contribution is the identification of semi-public space in the form of church and theater interiors, palace courtyards, entries and stairways. Until relatively recently (1970s) palace courtyards were open to the public, so that all white areas in the Grande Pianta represented the continuum of accessible urban space. In the memory of this author, walking through Rome taking shortcuts through courtyards to reach one’s destination was one of the delights of living here.

The location of some of these passageways and their alignment with existing street-axes suggests the presence of medieval streets, since absorbed by private buildings. One example:
Via del Paradiso (NN 628) lines up with the entryway of Palazzo Massimi alle Colonne (NN 625). The connected courtyards leading to Piazza dei Massimi suggests the former presence of a street which once linked Campo dei Fiori to Piazza Navona.

Palazzo Massimi (NN 625) aligning with Via del Paradiso (NN 628)

Unbeknownst to him, Nolli picked a fortunate time for the production of his map. Rome had gone through a period of substantial urban development since the mid-15th century. The mid-18th century marked the beginning of a long period of stasis when few major urban changes occurred within the city. Thus the Grande Pianta summed up all of the urban development of the Renaissance and Baroque periods, and remained a valid representation of the city until Rome became the capital of Italy in 1870. It is still the most useful map for studying Rome’s historic center.

 
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