Barby (French pronunciation: [baʁbi]) is a commune in the Ardennes department in the Grand Est region of northern France.

[5][6] The Aisne river passes through the south-east of the commune forming a small part of the south-eastern border as it flows west to eventually join the Oise at Compiègne.

The Ruisseau de Bourgeron flows from the north-east through the commune and the village and joins the Aisne on the southern border.

The Canal des Ardennes is parallel to and south of the Aisne and forms a small portion of the southern border of the commune.

Excavations have uncovered a Bronze Age tomb in Barby and the village is traversed by the old Roman road from Rethel to Château-Porcien.