Walhain is a Walloon municipality of Belgium located in the province of Walloon Brabant. It consists of the former municipalities of Nil-Saint-Vincent-Saint-Martin, Tourinnes-Saint-Lambert and Walhain-Saint-Paul.
The Belgian National Geographic Institute, the Belgian national cartographical service, calculated that the geographical centre of Belgium lay in this municipality, in Nil-Saint-Vincent at 50°38′28″N 4°40′05″E.[2]