Jemeppe-sur-Sambre  Jemeppe-sur-Sambre () is a Walloon municipality located in the Belgian province of Namur. On 1 January 2006 the municipality had 17,990 inhabitants. The total area is 46.80 km², giving a population density of 384 inhabitants per km². Apart from the village of Jemeppe-sur-Sambre itself, the municipality contains the localities of Ham-sur-Sambre, Moustier-sur-Sambre, Spy, Mornimont, Balâtre, Onoz, and Saint-Martin. The Grotte de Spy is located in the municipality near the village of Spy. The medieval Balâtre Castle is in the village of Balâtre, and Mielmont Castle in Onoz.