Origin and history
The Gallo-Roman ruins of Champlieu, located in the commune of Orrouy (Oise, Hauts-de-France), are an archaeological site classified as a historical monument since 1846. Located 2 km north of the present village, on a plateau at more than 130 m above sea level, the site consists of three separate buildings: a theatre in the Hemicycle (capacity: 3,000 squares), 2nd century thermal baths, and a Romano-Celtic temple evolving since the pre-Roman period (La Tene, 2nd-I century BC). These remains, crossed by the Brunehaut roadway, suggest the existence of a vicus (small agglomeration) or a rural sanctuary linked to the Suessions, the Gaulish people of the region.
The first records of the site date back to the 16th century, with vague descriptions evoking "considerable ruins". Father Claude Carlier, in the 18th century, led the first summary excavations and deplored the partial destruction of the remains for agriculture. In the 19th century, private excavations (Mr Georgette du Buisson, 1820-1826) and state (directed by Eugène Viollet-le-Duc in 1850 under Napoleon III) revealed ritualized objects (currency, bas-reliefs, capitals) and partially released the temple and theatre. The thermal baths, later identified (1862-1868), complete the site's understanding, although their results were only published in the 20th century.
The modern countryside (1977-1981) confirms the superimposition of three temples on the same site: a pre-Roman wooden sanctuary (La Tene), a Romanized fanum (I century BC), and a stone temple on podium (II century). The theatre, contemporary of the first fanum, and the thermal baths, built on an ancient artisanal district, illustrate the progressive urbanization of the site. Despite controversial restorations (especially in the 19th century) and recurrent looting (metal detectors), the site remains freely accessible. Today, only fragmentary remains remain: the temple chéneau, the bases of the thermal walls, and the partial structure of the theatre, including the upper steps.
Archaeological furniture, once preserved in situ, was transferred to the Musée Antoine Vivenel in Compiègne in the 1970s to protect it from theft and erosion. The carved blocks (mythological fronts, canned columns) and ritual objects (lacrymatory, Diocletian medals) bear witness to Hellenistic influence and intense artisanal and commercial activity. The hypothesis of a nearby Roman military camp, advanced from the 19th century, remains debated, although potter ovens and iron armor were discovered.
The Champlieu site raises questions about its exact nature: conciliabulum (sanctuary imposed by Rome), forum (local development), or simple vicus (rural town). The aerial photographs reveal an early urban grid, but the habitat seems dispersed, centered around public buildings. The Brunehaut roadway, an ancient road prior to the agglomeration, played a key role in its settlement, despite a less direct route than other Roman roads in the region. The abandonment of guarding in 1981 increased the vulnerability of the site, now protected by gendarmerie patrols.
Architectural interpretations remain partially speculative, especially for the temple, whose closed peristyle (opened bay wall) surprises archaeologists. This choice could be explained by the poor quality of local limestone, unsuitable for isolated columns. The theatre, nicknamed "horse iron" for its shape, and the thermal baths, equipped with a hypocauste and cement bathtubs, reflect an advanced romanization, while maintaining local features. The absence of vomitories (passages for spectators) in the theatre is explained by its modest size, while the carceres (loges) and sacella (chapelles) have never been attested.
