The cognitive art of rendering displays of complex data – design strategies in the Piazza San Marco

Visibility Graph Analysis of the Piazza San Marco in the context of neighbouring islands using Depthmap software1



Blog Entry I

‘…and the whole place in its huge elegance, the grace of its conception and the beauty of its detail, was more than ever like a great drawing room, the drawing-room of Europe profane and bewildered by some reverse of fortune.’
Henry James, The Wings of the Dove, 1902



How does visualisation yield the consequences of design choices, rendering powerful the values of design? How can we explain design excellence and make it accessible to others?


In the previous blog entry I visualised and explained the structure of the city of Venice as spatial network, gradually evolving through multiple actions of people over time. Central in this network and the life of Venice were the Piazza San Marco (the religious and political centre of Venice), and the Rialto (its commercial centre), two powerful hubs presiding over the spatial organisation and urban fabric of the city. If Venice was the outcome of the anonymous collective actions of society, its major civic spaces, such as the Piazza San Marco, were enhanced by acts of conscious design.

Monumental and majestic, the ‘great drawing-room of Europe’, as Henry James once called it, the Piazza San Marco is a layered ensemble of additions, extensions, alterations, superimpositions and expansions of all kinds. Yet, many of the interventions that led to its present form occurred in the sixteenth century when, after the appointment of the Florentine sculptor Jacopo Sansovino (1486- 1570) as state architect, an ambitious Renovatio Urbis (urban renovation) was inaugurated under the patronage of Doge Andrea Gritti (1455-1538).


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How did Sansovino’s scheme respond to these properties? How did he consider the role the Piazza played in the Venetian sense of identity and the everyday life of people in Venice? Before presenting the analysis of the Piazza San Marco, it is essential to emphasise some key ideas: First, for the Venetians, this place was intertwined with Venice’s Myth as the most Serene Republic through the slow accretion of buildings, structures and material forms, intended to reinforce the shared beliefs,

communal values and memory associated with St, Mark the Evangelist and the political institutions of the city.

Second, the transformations of the Piazza that took place in the sixteenth century were in essence a political project of celebrating the city’s sovereignty and endurance against foreign powers.

Third, these transformations mark the emergence of architecture as liberal art in the Renaissance through the redesign of major civic spaces in Venice and other Italian cities.

Fourth, the emergence of architecture as liberal art was based on its separation from building craft. This refers to the split of architecture from the traditional processes that had produced buildings and cities up to that period, distinguishing in this way, architects from manual building labour due to their ability to disseminate architectural knowledge through argumentation and inscriptions, that is, language and drawing. Alongside the split of architecture from building craft came its separation from the collective anonymous processes that have produced cities. Architects claimed authorship of their work as opposed to master builders and the guilds that passing down information to next generations by word of mouth, rather than inscriptions, did not claim authorial recognition.

Finally, the transformations in the Piazza have their origins in the concept of scenography in the Renaissance, a term invented by Sebastiano Serlio (1475- c. 1554), in his second book of Architecture, which was published in Venice in 1560 (English edition, 1611). Serlio’s innovations gave Renaissance architects a way to bridge Vitruvius’ Roman theatre with architecture. A number of theatres, buildings and squares were built at the time, still influencing the ways in which architecture and urban spaces are being designed.

Arranged theatrically, urban piazzas used perspective to unify art, architecture, public space, and make them synchronically accessible to the eye. Configured to accommodate performances and processions, the urban transformations in the Piazza were in essence a major project of aggrandisement of the city, superimposing Vitruvius’ ideal of a Roman forum on the medieval urban fabric.

In the next blog entry I will discuss the analysis of the visibility structure of the Piazza, as we see it in the figure, and compare it to how we navigate the city Venice as a perceptual world of three dimensions.


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1. Depthmap is a computer programme to perform visibility analysis of architectural and urban systems. Turner, A., 2004, “Depthmap 4 — A Researcher’s Handbook”, Bartlett, School of Graduate Studies, UCL, London,;


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