Royale Union Saint-Gilloise, commonly known as Union SG, Union Saint-Gilloise or RUSG, is a professional football club based in the Brussels-Capital Region of Belgium. The club was founded on 1 November 1897 in Saint-Gilles and is one of the most historically successful football institutions in Belgian football. It is affiliated with the Royal Belgian Football Association under matricule number 10 and traditionally plays in yellow and blue. Since 1920, the club has played its home matches at Joseph Marien Stadium, located in Forest, Brussels. The stadium is recognised for its historic character and close connection with the club's identity. Union Saint-Gilloise enjoyed its greatest period of success during the first half of the twentieth century, winning eleven Belgian league championships between 1904 and 1935. Its famous team, known as Union Soixante, recorded an extraordinary unbeaten run of 60 consecutive matches between 1933 and 1935, a record that remains a defining part of the club's history. After several decades outside the top division, Union returned to Belgium's highest level in 2021 following promotion from the second tier. The club quickly re-established itself among the country's leading teams and won its twelfth Belgian league championship in 2025. It has also returned to European competitions, competing against clubs from across the continent. Its football operations include the senior men's team, technical and coaching departments, player recruitment, youth development and other sporting activities. The organisation also works with commercial partners, supporters and local communities through its football and social initiatives. Union Saint-Gilloise maintains an official website providing club news, match information, fixtures, results, ticketing details, team updates and announcements. The club is operated through Royale Union Saint-Gilloise SRL, a Belgian private limited liability company. With its historic achievements, distinctive supporter culture, traditional stadium and renewed success in domestic and European football, Union Saint-Gilloise remains one of Belgium's most recognisable football clubs.