Royale Union Saint-Gilloise, abbreviated to Union SG, is a Belgian football club originally located in the municipality of Saint-Gilles, in Brussels, although since the 1920s it has been based at the Joseph Marien Stadium in the neighboring municipality of Forest. The club is one of the most successful in the history of Belgian football. The club won eleven Belgian championships between 1904 and 1935. The team colors are blue and yellow.