Champlieu, Archaeological site in Orrouy, France.

Champlieu is a Gallo-Roman site in Orrouy with three separate remains: a temple, a theatre and baths. The theatre's horseshoe-shaped seating arc is visible as a grass-covered earthen mound around a worn depression, where a partial ring of grey stone blocks and scattered stones mark the structure. The temple and baths lie nearby, crossed by the chaussée Brunehaut.

The site was already known as Les Tournelles by the late 16th century, when Nicolas Bergeron's Histoire de la maison royale de Valois appeared in 1583. In 1748 the abbé Claude Carlier unearthed Roman capitals there. Excavations by Georgette du Buisson between 1820 and 1826 and by Edmond de Seroux in 1850 brought out reliefs, column shafts and a tomb with bronze medals of Diocletian. The site was listed as a monument historique in 1846, and Eugène Viollet-le-Duc directed the clearing of the temple and the horseshoe-shaped theatre after 1857.

The name Champlieu comes from a hamlet 700 m to the southwest; the site was long called Les Tournelles. The Brunehaut road, of ancient but undatable origin, runs between the temple to the north and the arenas to the south, with the baths further south. The arenas' horseshoe shape was already recognised by scholars in the first half of the 19th century.

The ruins lie in open fields on a plateau 2 km north of Orrouy, reached by a road crossing the site; the Brunehaut road passes between the temple to the north and the theatre to the south, with the baths further south. The ground is uneven, with a grass-covered mound and stone blocks set into a worn depression. The Compiègne forest edge is about 300 m to the north-east.

The grass-covered mound that visitors take for a natural rise is the temple itself, still unexcavated; the archaeologist Georgette du Buisson dug into it between 1820 and 1826 and brought out Doric capitals, fluted column shafts and a tomb lid carved with leaves. The hard limestone of the temple came from quarries at Senlis.