The urban renaissance is the study of urban transformations made during the Renaissance, between the fifteenth and sixteenth centuries, and theoretical discussions about the city developed during this period.

Theories of the ideal city
A new and essential feature of Renaissance architecture was the theoretical elaboration of the form to be given to the city. These reflections, expressed in writings, schemes and treatises, are generically summarized under the definition of ” ideal city ” and identified in the central symmetry radial scheme in relation to the research on the central plan which, with the consequent symbologies, characterizes the most advanced between the fifteenth and sixteenth centuries.

The idea of giving the city an orderly and rational form, making it a symbol of the artistic and philosophical conception of the whole Renaissance, slowly matured in the works of the fifteenth century treatises, starting with Leon Battista Alberti.

The first to give a rigorous geometrical scheme for a utopian and fantastic city was Filarete who, in his treatise, designed the Sforzinda plant, with a radial type scheme that will characterize all subsequent theories. However in Sforzinda the dimensional scale of the city is enormous compared to the cities of the time and does not allow Filarete a clear definition of urban spaces and the building fabric for which no indication, perhaps failing to reconcile the radial structure of the main roads with the implied orthogonal mesh of the representation of the center of the city.

Francesco di Giorgio Martini proposes a repertoire of symmetrical and rigorous forms, combining radio-centric and chess-based installations and taking into account the new defense needs bastioned by artillery. It was precisely the evolution of “modern” fortification techniques, due to the introduction, starting from the fifteenth century, of firearms, which will give, to the Renaissance idea of a radiocentric city, the possibility of materializing in concrete realizations.

After him, Sebastiano Serlio, Andrea Palladio and Vincenzo Scamozzi also tackled the theme of the city defined geometrically and perfectly in its central form.

The achievements
Urban constructions between the fifteenth and sixteenth centuries were rather far from theoretical schemes, even if they were characterized by the will to determine spatial relations through geometry.

In concrete realizations, first in Italy and then in Europe emerges the need for wider ways and regular public spaces and the search for symmetry and urban decorum. The “regularity character” is also recurrent in the urban planning regulations of the fifteenth-century citizens’ statutes. There are many interventions rectification and expansion of existing roads (to Rome to Via Lungara, Via Giulia, Via del Corso, Via del Babuino, Via di Ripetta) and the creation of new public spaces or the geometric regularization of existing ones. At the same time they improve the functional and hygienic standards of the city with the construction of aqueducts and canals and the construction of stone paving for the streets.

These characteristics are also linked to representative needs and to the widespread and progressive centralization of power in the figure of the “Lord”, patron and patron, which also determines the definition of the “urban” city as well. Also born the “ghettos” neighborhoods differentiated for the Jews.

The urban structure is also enriched with new types of buildings, and in particular of stately buildings, but also hospitals.

The new concept of public spaces can be exemplified in the creation of new squares characterized, generally, by a unitary design, by inten- tive elevations and symmetry. For example, there is the Piazza della Santissima Annunziata in Florence and the Piazza Ducale di Vigevano.

The most studied complex experiences are the transformation of Pienza, carried out by Bernardo Rossellino and the expansion of Ferrara (1492) by Biagio Rossetti, which proposes wide streets in contrast with the medieval tradition.

The founding cities
The cities of foundations of the Renaissance period are very few and built from the second half of the sixteenth century, especially for defensive reasons.

Among the works of the sixteenth century some of them resort to the traditional orthogonal scheme, without resorting to centralized forms: Terra del Sole, commissioned by the Grand Duke of Tuscany Cosimo I de Medici, Cortemaggiore, Gattinara, Acaya and Carlentini. Others such as Guastalla and above all Sabbioneta, built at the end of the 16th century at the behest of Vespasiano Gonzaga conciliate a layout based on orthogonal axes with a polygonal perimeter.

In fact, the theoretical research about the shape of the city, following the example of Francesco di Giorgio Martini, quickly oriented towards the geometric definition of the urban form entrusted to the fortified perimeter which in turn following the research of the so-called modern fortification, became polygonal, towards increasingly complex shapes up to the starry configuration. The geometric and utopian ideal of the Renaissance city was transplanted into the technique of fortifications, surviving as a form and not as a symbolic image, to the contact of precise functional needs. Many of the schemes produced, for example by Pietro Cataneo, represent an attempt to reconcile a radiocentric scheme with an orthogonal, in the footsteps of Francesco di Giorgio Martini. Although on a pre-existing nucleus, even the city of Livorno can be considered a Renaissance foundation involved in the characteristics of the works of the late sixteenth century in which the polygonal defensive perimeter determines the shape of the city that inside presents orthogonal traces. There are also numerous buildings of new walls, equipped with bastions and polygonal shape, to defend existing cities.

Outside Italy it is possible to mention the achievements of Vitry-le-François (1544), Phalsbourg (1570), Freudenstadt (1599), Lixheim (1606). Some of them represent an alternative scheme to the polygonal one, based on the square with a square in the center and two orthogonal axes that is affected by the description of the castrum made by Vitruvius and by Durer’s research on the “square city”.

The only city built in the late sixteenth century, with a clear radiocentric scheme, was Palmanova built by the Venetian Republic, whose geometric design was replicated after a few decades in Coevorden in the Netherlands.

The utopians
Parallel to the work of the treatise architects, the ideal city in which the geometric conformation is an expression of the perfection of social organization is the object of the elaboration of numerous utopian thinkers. In particular, the works of Tommaso Moro (Utopia) and Tommaso Campanella (La città del Sole) must be mentioned

Post-Renaissance accomplishments
The radiocentric model of the ” ideal city ” elaborated, starting from the fifteenth century, by the Renaissance treatises, therefore had few applications during the sixteenth century. However, he survived in the treatises, also due to the coincidence with the starry forms of the city walls that had come to the elaboration of modern fortification. Thus, in the seventeenth and eighteenth centuries, urban centers arose in which the polygonal form of the fortifications was accompanied by a geometric scheme of the urban organization, of the orthogonal type but also of the radiocentric type. This coincidence between the search for forms suitable for fortification and the one related to the form of the settlement finds a conclusive point in the work of Vauban as the new fortified cityNeuf Brisach, with a starry shape.

In addition to the needs of fortifications, new urban centers were born, in the seventeenth century, for different causes, but almost always using the checkerboard pattern or, in any case, mainly orthogonal:
to repopulate areas of large estates like many dozens of settlements built in Sicily since the end of the sixteenth century, including Vittoria, Leonforte, Barrafranca, Niscemi, Riesi, Valguarnera, Cattolica)
as a reconstruction following earthquakes: among these Cerreto Sannita and the founding cities was in Sicily, in the aftermath of the tragic earthquake of 1693 that destroyed Noto and the other towns of the Val di Noto. The most interesting were Avola designed by Angelo Italia and Grammichele whose design is attributed to Carlos de Grunembergh whose urban layouts, of hexagonal shape, can be inferred from the Renaissance treaty of military architecture then known: The Four First Books of Architecture by Pietro Cataneo.
foundation initiatives of neo-feudal mold, in Italy (Santo Stefano di Camastra, seventeenth century), as well as in France (Henrichemont, Richelieu, Charleville in the seventeenth century).

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