Steel "pyramids". Lafuente's architectural experimentations in the 1970s

The buildings shaped as inverted pyramids spread in the second half of the 20th century across several countries proposing an original configuration: a sequence of tapered floors from top to bottom according to the inverse arrangement of the masses that reversed the traditional relationship with the ground. Also Italian architecture gave an important contribution to this structural type and an iconic example was the construction of the Esso Headquarters in Rome in 1980, designed by Julio Lafuente who used this building arrangement also for other works. This essay describes, through the works of Lafuente, the contribution of many architects and engineers to the development of inverted triangular prism shape and the research of related steel structures. Archive sources, bibliographic documentation and the comparison with other buildings in international contexts are used to analyse the development of these unusual “pyramids”.