Seen as a symbol of integration between structural and architectural invention and conveyed in leading national and international magazines, the Palazzo del Lavoro has fascinated entire generations. In emphasising, with a certain mannerism, the over-exhibited role of the structure, to the third phase of Nervi's design activity, that of the large international commissions in which the 'Nervi style' became a repertoire of solutions to be used worldwide.
The contract-competition for the construction of the 47,000 square metre pavilion that, for the Centenary of the Unification of Italy, was to host the great exhibition on labour presided over by Giovanni Agnelli and designed by Gio Ponti, was announced in July 1959. In October, the jury awarded the contract to the firm Nervi & Bartoli, with designers, in addition to Nervi, his son Antonio and Gino Covre, one of Italy's leading metal structure engineers. The project is centred on the subdivision of the square roof into sixteen independent umbrella-shaped elements of 40 metre sides separated by continuous strips of skylights and consisting of a radius of steel beams and a central pillar of variable geometry, a recurring feature in Nervi's works from the Corso Francia viaduct in Rome (1960), to the Savona railway station (1961) and the vault of San Francisco Cathedral (1970). The perimeter gallery, on the other hand, consists of isostatic ribbed floors typical of Nervi's work, made with mobile ferrocement formwork, according to a procedure already widely experimented by Nervi in various buildings including the Lanificio Gatti (1951-53). The proposal is convincing for its simplicity and structural legibility and, thanks to the modular solution and the differentiation of materials, is the only one capable of guaranteeing compliance with the very tight construction schedule. As had been the case for Torino Esposizioni, the construction management is ensured by FIAT's Construction and Plants Division, headed by Bonadè Bottino, with whom a relationship of mutual trust had been established. Apart from the technical data, which is nevertheless impressive - 158 metres wide by 26 metres high and 650,000 cubic metres in volume - the most innovative aspect is in fact the site organisation. Started in February 1960, by the end of December the building was already finished.
