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The House of the Opus Craticium, also known as Casa a Graticcio or the House of the Wooden Partition, is a remarkable example of ancient Roman residential architecture in Herculaneum, distinguished by its extensive use of the opus craticium construction technique—a timber-framed method filled with rubble and masonry for cost-effective and space-efficient building. Dating primarily to the 1st century AD with roots in earlier Samnite structures, this multi-story house reflects the urban pressures of ancient Herculaneum, where population growth and post-earthquake reconstruction necessitated adaptable, affordable housing. Unlike the more opulent villas in Pompeii or Herculaneum, it served as a modest apartment block, housing multiple families or tenants, and is one of the few fully preserved examples of opus craticium on both ground and upper floors. Buried under layers of mud and pyroclastic material during the AD 79 eruption of Mount Vesuvius, the house was excavated in the early 20th century and offers valuable insights into Roman engineering, domestic life, and socio-economic adaptations. Its significance lies in demonstrating a transition from single-family homes to multi-unit dwellings, highlighting the ingenuity of Roman builders in a seismically active region.
The House of the Opus Craticium is situated in Insula III (block III), on the west side of Cardo IV Inferiore, one of Herculaneum's main north-south streets. Its entrances are at III.13-15, making it easily accessible within the excavated area of the ancient city. The house is enclosed between two older Samnite houses and is adjacent to the Casa dello Scheletro (House of the Skeleton) to the south. This location in the lower part of Herculaneum, near the Suburban Baths and the ancient shoreline, provided residents with proximity to commercial and public amenities while exploiting the site's natural slope for structural support. Coordinates are approximately 40.8060° N, 14.3475° E, within the Ercolano Archaeological Park, about 10 km southeast of Naples and near modern Ercolano town. Its urban placement underscores the dense, mixed-use nature of Herculaneum's neighborhoods, where residential spaces often integrated with shops and workshops.
The house's origins trace back to the Samnite period (likely 2nd
century BC), when it may have been a small single-family atrium
dwelling. Significant remodeling occurred after the devastating AD 62
earthquake, which damaged much of Herculaneum and Pompeii, prompting
rapid reconstructions to accommodate a growing population. This period
saw the adoption of opus craticium for its speed and economy,
transforming the structure into a multi-apartment building with
commercial spaces on the ground floor. The house belonged to Octavia
Philadelphia, as indicated by nearby inscriptions, reflecting ownership
by freedmen or middle-class residents. Buried in AD 79 under a thick
layer of hardened mud (tuff-like pyroclastic surge), it was better
preserved than many Pompeian structures, which suffered from collapsing
roofs under ash weight.
Excavations were led by archaeologist Amedeo
Maiuri from 1927 to 1933, revealing the house's unique timber framing
and interior details. The site's preservation allowed for the recovery
of organic materials like wood and furniture, rare in other Vesuvian
sites. Post-excavation, the house has been studied for its construction
techniques, with recent analyses (e.g., 2019 research) emphasizing its
role in understanding Roman seismic adaptations. As of August 25, 2025,
it remains a key attraction in the park, with ongoing conservation to
combat erosion and tourism impacts.
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The House of the Opus Craticium exemplifies the opus craticium
technique, a Roman wall-building method using a timber skeleton of
vertical posts (arrectaria, 8–12 cm square) and horizontal beams
(transversaria, 6–8 cm wide), connected by mortise-tenon joints and
rivets, without diagonal bracing. Frames, 50–80 cm thick, are filled
with rubble, concrete, bricks, or yellow tuff blocks (opus
incertum), often on a stone or brick plinth to prevent dampness.
Exterior surfaces were finished with multi-layer lime-based plasters
(opus albarium) for durability and aesthetics. The house stands two
stories tall (ground floor 2.95 m, upper 2.90 m), supported by opus
incertum and brick piers for stability, allowing thin partition
walls that saved space and enabled flexible layouts.
The entrance
passageway connects to a taberna (shop) on the left and a central
courtyard serving as a light well, with an impluvium for rainwater
collection leading to an underground cistern. Stairs on the right
access upper apartments, while dimly lit rooms flank the courtyard.
The structure was divided into at least two apartments: a small
two-room flat with balcony access, and a larger five-room unit with
windows overlooking neighboring properties. Features include
overhanging balconies (maeniana) for additional space, a small
cenatio (dining area), and diaeta (day room). This design reflects
post-earthquake innovations for quick, lightweight construction,
ideal for upper floors and urban density, though vulnerable to fire
and decay.
Decorations are modest, befitting a middle-class dwelling, with
surviving Fourth Pompeian Style wall paintings in the upper
apartments—characterized by intricate panels, architectural
illusions, and possibly mythological motifs, though many rooms
remain undecorated and dimly lit. The plasters and finishes on the
timber frames provided a smooth, painted surface, enhancing the
illusion of sturdier masonry.
Artifacts highlight domestic and
religious life: preserved wooden furniture including beds (one
child's), cupboards, and bronze statuettes of deities such as
Jupiter, Fortuna, Aesculapius, Diana, Minerva, and a pair of Lares
(household guardians) holding drinking horns. A notable find is an
oscillum—a half-moon-shaped marble plaque carved on both sides,
possibly depicting Dionysian scenes, similar to those in other
Herculaneum houses. These items, carbonized by the heat but
preserved in the mud, offer rare glimpses into everyday Roman
interiors, with the religious figurines underscoring household
piety.
As of August 25, 2025, the House of the Opus Craticium is open to the public within the Ercolano Archaeological Park, managed by the Italian Ministry of Culture. It is well-preserved due to the protective mud layers, though ongoing conservation addresses humidity and structural decay in the timber elements. Visiting hours align with the park: 8:30 AM to 7:30 PM (March 16–October 15) or 8:30 AM to 5:00 PM (October 16–March 15), with last entry 90 minutes before closing. Admission is €13 for adults (free for EU citizens under 18 or over 65), or included in combined tickets with Pompeii (€22). Guided tours are available, often focusing on Herculaneum's unique preservation; audio guides (€8) and apps provide self-paced exploration. The site is moderately accessible, with ramps in some areas, but uneven terrain may challenge those with mobility issues—contact the park for accommodations. Visitors praise its authenticity and the visible timber framing, rating it highly for educational value, though crowds can form during peak seasons (spring/fall). Combine visits with nearby sites like the Villa of the Papyri or Pompeii for context. Photography is allowed without flash, and modest dress is recommended.