Bird's-eye view of Tuscany (and part of Umbria) with the Val di Chiana (and Lake Trasimeno), between Arezzo, Volterra, Siena, Sovana, Chiusi, Cortona and Sansepolcro, c. 1502.

This folio dates from the time when Leonardo was traveling through Tuscany and Central Italy as architect and engineer plenipotentiary to Cesare Borgia. Considering the cool accuracy of the approach and the execution of details, the handwriting from left to right, the distorted misrepresentation in the lower right-hand part to include the datum points of Lake Bolsena and the Tyrrhenian Sea, this map seems to be an illustrative support to the presentation of a project for governing the watercourses on the Val di Chiana in relation to the Arno in particular, as well as to Lake Trasimeno and the Tiber River. It may also relate to a strategic plan involving the rivers between the left bank of the Arno, the Cecina and the Ombrone Grossetano.

Significant – as in map RLW 12682 – is the importance of the watercourse downstream of Cortona, between the Val di Chiana and Lake Trasimeno, which is linked to the note on folio RLW 12277: «Braccio da Montone closed it». This note on the ancient conformation of the Tuscan-Umbrian region confirms Leonardo's vision of prehistoric Tuscany, and in particular of that Val di Chiana recalled by Torricelli as «truly resembling the sea», which Leonardo's utopian vision translates into a reservoir serving to regulate the Arno's flow and to make the Florence Canal navigable. Highly interesting is the relationship between the great basin of the Val di Chiana and its tributaries between Ponte alla Nave, to the north, and Ponte a Valiano, to the south.

Excluding those relevant to Umbria, 254 place names have been found, including cities, strongholds and watercourses distributed over the following geographic areas: Aretino, Casentino, Chianti, Florence and surroundings, Grossetano, Livorno and surroundings, Middle Valdarno, Senese, Val d’Arbia, Val d’Orcia, Val di Cecina, Val di Greve, Val di Pesa, Valdelsa, Valdera, Val di Chiana, Valtiberina, and Volterrano.

Bird's-eye view of western Tuscany with the coastline from Campiglia and San Vincenzo to Lucca, showing the surroundings of Pisa, Livorno, Volterra and the Valdera, c. 1503.

Illustrative map on which the place names are entered in normal handwriting. Below, on the right bank of the Arno, in the area between Vicopisano, Castelfranco, S. Maria a Monte and S. Croce, and thus amidst the marshlands of Bientina and Fucecchio, the strongholds and towns are indicated without naming them (although Vicopisano is recognisable). This detail is one reason for excluding this map from the drawings finalised at deviating the Arno into the Florence Canal through the Valdinievole. Obviously, it is instead a demonstrative map for the project for deviating the Arno away from Pisa toward the Stagno di Livorno. The representation of the Port of Livorno is remarkably realistic, also in relation to a youthful sketch in the Codex Atlanticus (f. 147a-r). The scale is around 1:200.000.

There are 101 cities, strongholds, individual buildings, watercourses and lakes, distributed over the following geographic areas: Livorno and surroundings, Lucchesia, Pisa and surroundings, Volterrano and Valdera.

Map of northwestern Tuscany (from Florence to Barga, Ripafratta and Bientina) with studies for deviating the Arno into the Florence Canal, through Prato, Pistoia and Serravalle, c. 1503.

An illustrative and demonstrative variation (with place names entered in ordinary handwriting) of map RLW 12279, which precedes the more precise one found in Madrid Ms. II on folios 22v-23r. The representation is almost identical from Florence to Serravalle but seems here to involve the Padule di Fucecchio and only to touch on the marshes of Bientina. Among the approximations and inexactitudes, Montalbano is shown perpendicular to the course of the Arno. In the left margin appears a scale equivalent to around 1:217/230.000, which is constant and closely coincides with reality, except in the western territory, where the distances seem to have been determined with a scale fluctuating between 1:160.000 and 1:190.000 (from Bientina to Lucca is 8.9 cm on the map, which should equal approximately 13 Florentine miles, i.e., about 21.5 km, but the real distance is 17 km); from Bientina to Florence instead the distance on the map is 21.7 cm, equivalent to approximately 31 miles (around 51 km), while the real distance is 52 km. Florence is represented without a name, but is clearly recognisable, also for the Cathedral with its dome, as is Poggio a Caiano with its Medicean Villa. Among the various localities, the stenographic sketches of places evidently well known to Leonardo, such as Vinci and Bacchereto, Fucecchio and Ponte a Cappiano, and the square layout of cities such as Empoli, are remarkable for their realism.

Among the most evident inexactitudes on this map are, strangely enough, the erroneous positions of buildings well known to Leonardo, such as the Abbey of San Giusto and the Hospital of Sant’Alluccio on Montalbano, reference points in his youthful journeys and his reconnaissance for the deviation of the Arno.

There are 55 cities and strongholds distributed over the following geographic areas: Florence and surroundings, Lucchesia, Middle Valdarno, Montalbano, Prato-Pistoia, and Valdinievole.