The city of Venice has been caught in a tug of war between progress and traditionalism for many years, and particularly since the construction of a railroad viaduct in 1846 linked the island city to the Italian mainland for the first time in its history. Over a century later, the Venetian government commissioned Louis Kahn to design a new Palazzo dei Congressi for the city; his proposal, while paying respect to the histories of both the Republic of Venice and a unified Italy, could not escape similar controversy.
Kahn began the design process not with drawings, but with sculpture. Using clay, he constructed a model of Venice that showed only three landmarks in recognizable detail: Piazza San Marco, Le Corbusier’s contemporary scheme for a hospital (another project which would never come to fruition), and Kahn’s own proposal for the Palazzo. The initial site proposed by the city, as shown in this clay rendering, was the Biennale Giardini near the eastern tip of the island; when this location was rejected, Kahn was then asked to propose a new design in the Arsenale, a former military compound which was already owned by the city.
Although the change of site forced Kahn to start over, it also afforded him the opportunity to make a more poetic architectural maneuver: rather than set it in the heavily-wooded landscape of the Giardini, he was able to turn the Palazzo into a bridge that spanned across the Canale delle Galeazze. The public space that would originally have been found in the Giardini transformed into a roof terrace, allowing the structure to act as both Palazzo and piazza in a single dramatic gesture.
Kahn’s proposal for the Arsenale was striking in its simplicity. Two rectangular masses rose from opposite banks of the canal, each containing stairways to bring visitors to the congress hall. The hall itself was suspended between the two stair towers, its floor sloping gently toward the center of the space. Above, three shallow vaults ran transverse to the longer curve of the floor; similar vaults would appear in another of Kahn’s projects, the Kimbell Art Museum, which would open in 1972 – Kahn’s last year of involvement with the Palazzo dei Congressi project.[4, 5]
These vaults were surfaced in lead – a design decision inspired by another Venetian building. While giving a lecture on the roof of the Palazzo Ducale (the Doge’s Palace), Kahn noted the curved lead roofing of the nearby San Marco Basilica, which had stood firm for a thousand years. This was, by his reckoning, proof that the material was equally suitable for use in a new building. Although the Palazzo dei Congressi was never built, the concept would not disappear with it; as with the form of the roof, the material finish would also be translated to the Kimbell Art Museum.
Perhaps the most distinct aspect of Kahn’s proposal was its sloped floor. This form would have been achieved using a post-tensioned concrete slab, the curve of which would have been visible from both inside and outside the building. Although this idea was already present in the first iteration of the design, it gained greater visual rationale in the final version; its curve, rather than sitting atop a series of ground-level artist workshops, instead emphasized its suspension above the waters of the canal.
The example for the lead-lined roof vaults may have originated in—or been inspired by—the city of Venice, but it was in another Italian city in which Kahn found his inspiration for the congress hall. The Piazza del Campo in Siena, dating back to the end of the 13th century, is famed for the shell-like concave dip in its paving. This shell is laid with nine radiating strips of travertine stone, representing the Government of the Nine that ruled the city for eighty years. Siena’s civic center is not an uncommon source of inspiration for civic buildings, having been referenced by architects like Alvar Aalto to name only one; it is perhaps not surprising, then, that Kahn saw the Campo as a worthy subject on which to base his own design.
While Kahn was commissioned at the Mayor’s behest, and worked closely with the local government throughout the project, his proposal was ultimately rejected by city officials after six years of work. Much like Le Corbusier’s hospital, the Palazzo dei Congressi was deemed too anomalous of an element to blend into the historical urban fabric of Venice; the design’s references to Venetian and Sienese landmarks were an insufficient counter to its undeniable formal Modernity. The city’s health commissioner, Vito Chiarelli, had written a letter to Kahn shortly after the architect was commissioned specifically to warn him that Venice had an “innate inability to accept abstract forms embedded in its historic context.”
Many contemporary projects in the vein of Kahn’s fell victim to Venice’s mid-century historicism, never progressing beyond models or the drawings. It is up to the observer to determine if this obstinate preservation of the city’s pre-war urban fabric was justified, or if new landmarks like Kahn’s Palazzo dei Congressi could have captured a new architectural glory to rival that of the splendour, and innovative attitude, of the former Venetian Republic.
While visual materials are few and far between, you can visit this source to see a number of photographs and drawings of this unrealised project.
 Cessi, Roberto. “Venice - History." Encyclopedia Britannica. Retrieved May 30, 2016. [access].
 McCarter, Robert. "Demanding a Presence: The Unbuilt Works of Louis I. Kahn." Lecture, CUNY Spitzer School of Architecture, New York, February 21, 2013.
 Fracalossi, Igor. "AD Classics: Kimbell Art Museum / Louis Kahn." ArchDaily. March 31, 2011. [access].
 "Piazza Del Campo - Siena, Italy." ItalyGuides. Accessed May 29, 2016. [access].
 "Piazza Del Campo." Tuscany Pass. Accessed May 29, 2016. [access].
 Ainsworth, Troy Michael. Modernism Contested: Frank Lloyd Wright in Venice and the Masieri Memorial Debate. PhD diss., Texas Tech University, 2005. p298-299.