As a major port, Ostia was integral to Rome’s supply chain, necessitating the development of specialized structures for storage, commerce, and manufacturing. Many of these buildings were directly linked to maritime trade, benefiting from the city's proximity to the Tiber River and its extensive harbor facilities.

Ostia Antica’s commercial and industrial structures reflect its function as Rome’s primary harbor city, where vast quantities of goods were stored, processed, and traded before being transported to the capital. The Plaza of Corporations, located behind the theatre, served as a hub for maritime trade, with offices representing shipping companies and merchant guilds from across the empire. Large warehouses, such as the Grand Warehouse and the Warehouse of Epagathus and Epaphroditus, stored vital commodities like grain and olive oil, while shops and markets catered to local and visiting traders.

Industrial production was also significant, with facilities like the Mill/Bakery of Silvanus, where grain was ground and baked into bread on an industrial scale, and the Fullonica on the Augustan Road, which processed textiles through washing, dyeing, and finishing techniques. These structures, strategically located near major roads and transport routes, illustrate Ostia’s economic complexity and its role in sustaining Rome’s vast population. The archaeological remains of these buildings provide critical insights into the organization of commerce and industry in the ancient Roman world.

circa 250 BCE

Macellum
The Macellum of Ostia Antica, a central market for fish, meat, and vegetables, was excavated between 1938 and 2001 CE, with restorations and further investigations revealing multiple construction phases. The earliest remains date to the third century BCE, followed by a late Republican structure (circa 70–30 BCE), possibly a domus, both destroyed by fire. The standing remains primarily belong to a Commodus-era (circa 180-192 CE) building, with later modifications in the fourth and fifth centuries CE. The Augustan period saw the construction of shops beneath the eastern half of the courtyard, indicating commercial continuity at the site.

The market was organized around a large central courtyard (measuring approx. 28 x 22 meters), paved with marble and featuring a rectangular basin with a putto-on-dolphin statue. The north section housed shops, including the Shops of the Fishmongers, with evidence of commercial counters and porticoes. The western side contained a deep podium with Corinthian columns, possibly for official market functions, weights, and measures, while the southwestern area featured a vaulted room for standardizing goods. Later additions included glass furnaces in the late fourth or early fifth century CE, indicating industrial activity. The Macellum is referenced in multiple inscriptions, with documented restorations in the early first century CE by Nymphodotus, a freedman of Augustus, and in the second century by Publius Lucilius Gamala, reinforcing its long-standing economic significance in Ostia.

circa 90 BCE

Republican Era Warehouse
The Republican warehouse (Magazzini Repubblicani), a commercial complex was built at the end of the first century BCE, probably in connection with the river port to its north. During the first phase, it consisted of a rectangular building in opus qausi reticulatum surrounded by a portico with tufa pillars. Also connected to the warehouses was the Caseggiato del Cane Monnus, which had tabernae (shops) opening onto a portico. In the imperial period, the warehouses underwent a series of radical alterations, the most important of which was the transformation of their northern part into the Terme dei Cisiarii; the original internal level, lower than that of the surrounding buildings, probably remained unchanged.

circa 41-45 CE

Grand Warehouse
The large or grand warehouse (Grandi Horrea), Ostia's largest commercial building, is traditionally dated to the period of the emperor Claudius (circa 41-45 CE), though recent studies have proposed an initial date in the first century BCE. It had a porticoed courtyard with tufa columns, around which the cellae (storage chambers) were arranged on three sides. It was completely rebuilt between the late second and early third centuries CE, when the brick walls were renovated, two parallel rows of cellae were added in thecentre of the courtyard and the second story was constructed. At thistime, the floors of all the cellae were raised using suspensurae (little brick pillars), thus creating a space thatinsulatedthe grain stored here from damp.

circa 50 CE

Plaza of Corporations
The Plaza of the Headquarters of the Corporations (Piazzale delle Corporazioni) was a vast square open towards the Tiber and was designed together with the theatre in the Augustan period but was equipped with porticoes only during the time of Claudius (mid first century CE). Towards the end of the first century CE, a temple on a high podium with two Corinthian columns at the front was built at the centre of the square. Though the identity of the deity is not known with certainity, it is speculated that the temple was dedicated either to the goddess Ceres or the divinized royalty. Another transformation took place in the first half of the second century CE, when the portico was doubled and the earliest floor mosaic were laid; the latter were later remade when the internal space was subdivided into different rooms. The motifs depicted were linked with commercial activities; the presence of the inscriptions mentioning the corporations of the traders, ship-owners and entrepreneurs from both Ostia and elsewhere support the theory that these were the headquarters of the corporations themselves.

circa 120 CE

Mill/Bakery of Silvanus
The flour mill or bakery of Silvanus (Molino del Silvano), was used for the production and sale of bread. It was built in around 120 CE and destroyed by a fire in the late third century CE. It had six tabernae (shops) at the front. Whilst the inner rooms, floored with road paving stones, served to mill the flour and make dough, as we know from the presence of milstones and basins made of lava stone; the bread was baked in the corner room, which has a large oven. The bakery was connected directly to the grand warehouse (Grandi Horrea) on the opposite side of the street, where grain was stored. In the third century, an uncovered passageway behind the bakery was turned into a cult space for Silvanus, the popular god of fields and woods.

circa 125 CE

Fullonica on the Augustan Road
The Fullonica on the Augustan Street (Fullonica su via degli Augustali) was built in the early second century CE by converting a house of an earlier period. It consisted ofa huge room with a roof supported by pillars, hosting four large basins connected to one another and lined with cocciopesto, a coating that served to waterproof them. In the third century CE, 35 circular recipients in terracotta were added, separated by low brick walls against which the workers leant as the pressed the textiles with their feet. The fabrics were washed with a variety of substances, including natural soda and urine, which contains ammonia, and werehung out to dry on slender beams, as suggested by the presence of cavities in the sides of the pillars.

circa 145-150 CE CE

Warehouse of Epagathus and Epaphroditus
The warehouse of Epagathus and Epaphroditus (Horrea Epagathiana et Epaphroditiana) is known from an inscription to have been named after two freedmen (presumably its owners), Epagathus and Epaphroditus. This is the only warehouse in the Ostia Antica of which the ancient name is known from an inscription above the entrance. The storage complex can be dated to circa 145-150 CE (opus latericium). In the south wall part of the Castrum-wall was reused. The building was excavated and restored extensively in the years 1922-1923 and 1938-1940. Collapsed walls and piers were found on top of a layer of sherds and beaten earth, circa 0.70 high. The building was plundered in antiquity, witness holes in the vaults and higher parts of the walls.

circa 180-200 CE

Shop of the Fish-Seller
The shop of the fish-seller or the fishmonger (Taberne dei Pescivendoli) were built along the decumanus maximus. It was part of the northern porticus of the Macellum, the central market for fish, meat and vegetables. There are two sections, to the west and east of the entrance corridor of the Macellum. In the centre of both rooms is a marble table, and against the back wall a fish-basin revetted with marble, supporting small columns. In the eastern section is a black-and-white mosaic, with marine motifs; featuring a triton and a dolphin with an octopus in its beak.