Saint-Nicolas is a municipality of Belgium. It lies in the country's Walloon Region and Province of Liege. It is effectively a part of the greater Liège conurbation stretching west from Liège city centre towards Liège airport. As of January 1, 2006 Saint-Nicolas had a total population of 22,666. The total area is 6.84 km² which gives a population density of 3,313 inhabitants per km². It has the highest population density of any Belgian municipality outside the Brussels-Capital Region.