During the Renaissance authors of widely varying backgrounds wrote utopias. In the fifteenth and sixteenth centuries certain features of the utopias remained constant, but their aims varied as widely as their authors. One of those utopias, which seemed externally to fit easily within the framework of the Renaissance utopia but actually differed in important ways from all its fellows, was the "New World," contained in I Mondi (1552) of Anton Francesco Doni (1513-1574). After a short discussion of the general characteristics of the Renaissance utopias, this study will focus on Doni's "New World" in order to determine in what ways it fitted within the pattern of Renaissance utopias, and how it differed. Although Plato's suggestions in the Republic and the Laws for a well-governed city, social regulation, and educational reform were the ultimate roots of all Renaissance utopias, the practical starting point for the Renaissance was the abstract city models of the Quattrocento architects. These utopias exhibited two fundamental characteristics of the Renaissance utopia: a city plan of geometrical regularity, and regimentation of the lives of the inhabitants for the sake of the city as a whole. Leon Battista Alberti's De re aedificatoria (written in 1452, published in Latin in 1485 and in Italian in 1546) listed plans and ideas for an organic city in which the inhabitants could live in peace. His plans went beyond architecture to encompass social considerations, as he planned asylums for the poor, and separated different social classes from each other. More complete was the utopia of Antonio Averlino, called Filarete (c. 1400-1466), the architect of the Sforza castle at Milan. Filarete's plan for a perfect city, named Sforzinda for his patrons, was in the shape of a regular eight-pointed star with streets leading from the eight city gates located between the points of the star to the center of the city. Filarete placed the various shops and crafts in specified areas of the city, and regulated the color of dress and value of jewelry permitted to the nobility of Sforzinda. He devised social regulations for the schools and prisons with a communal utilitarian aim in view. However, Filarete's Sforzinda, the earliest complete Italian utopia, remained in manuscript until the twentieth century, and probably had no influence on other utopias.1