Potentially endless set of pieces.

Workshop at RomaTre University, School of Architecture in Rome.

In his History of Rome, Livy mentions a monumental porticus outside the Trigemina Gate in the southern part of the city,[1] a warehouse built along the Tiber in 193 b.C by the aediles M. Aemilius Lepidus and L. Aemilius Paullus (later restored in 174 b.C by the censors Q. Fulvius Flaccus and A. Postumius Albinus), completed by an Emporium, a market connected to the river harbor.
The archeologist Guglielmo Gatti in 1934 found possible traces of such a building in the fragments 23 and 24a-c of the Severian Forma Urbis Romae,[2] whose outlines presented rows of squared piers marked by an uncompleted inscription “lia” which Gatti integrated with [Aemi]lia implying a portion of the porticus described by Livy.
Recent studies have instead demonstrated that the homogeneous seriality and the sloped progression of the building could be attributed neither to a simple porticus, a covered passages supported by columns, nor to a traditional horrea, a stocking warehouse with courtyards and a single access, suggesting that its supposed commercial use emerged only at a later stage. The building instead most probably worked previously as military navalia, or an arsenal to recover war ships, made of sloping docks sheltered by a stepped roof and supported by a limited amount of linear supports.
Nevertheless, besides its doubtful origins, the building on the Tiber constituted the earliest known use of concrete at a large scale: an impressive extended structure covering approximately 25.000 squared meters through 50 barrel vaults in opus caementitium of 8.30m span. 294 tuff piers in opus incertum were arranged in 7 rows at different levels to protect the boats from the flood variations and ensuring sufficient aeration and light conditions through the articulation of the roof as in a modern factory, where all the facilities and technical paraphernalia are usually compressed either in the plinth or in the ceiling to leave the manufacturing floor totally uncluttered.
At the end of the XVIII century Giovanni Battista Piranesi conjectured different reconstructions of the porticus, operatively reusing the generative potential of the plan in his Ichnographia,[3] while in 1978 Rowe and Koetter briefly mentioned the porticus Aemilia among the 'potentially endless set of pieces' in their Collage City.
Yet the building remained largely underestimated, despite its experimental use of concrete and the absoluteness of its functional organization, harbinger of an architecture devoid of quality and reduced to a zero-degree language.
In this sense, the porticus manifested a radically new conception of space, a purely utilitarian structure - an architecture that simply coincides with what it does: no longer based on hierarchical compositions of orders, forms or rooms but on the horizontal continuity of an unique environment, able to host whatever activity, adapt to any topographical circumstance and shelter any forms-of-life within the measured intervals of its repetitive frame: an infrastructure that would rapidly become the algorithm for any space of production.

[1]Livy, History of Rome, XXXV, 10, 12; XL, 51, 4; XLI, 27, 8 The aedileship of Marcus Aemilius Lepidus and Lucius Aemilius Paullus [193 BC] was a distinguished one. They collected numerous fines from people illegally grazing animals on public lands and with that money…built a covered warehouse [porticus] outside the Porta Trigemina, fronted by a commercial market [emporium] along the Tiber.
[2] Guglielmo Gatti, “Saepta Julia e Porticus Aemilia nella Forma severiana”, Bullettino della Commissione Archeologica Comunale di Roma, 62 (1934), 123-49, esp. p. 14
[3] See Giovanni Battista Piranesi, Le Antichità Romane (1756) Pianta degli avanzi del Portico fabbricato da M. Emilio Lepido e P. Emilio Paolo fuori della porta Trigemina nell’Emporio alla ripa del Tevere, but also the Porticus Septorum Juliorum in his fictious Ichnographia Campi Martii, (1757-62).