Beersel is a municipality located in the Belgian province of Flemish Brabant. The municipality comprises the towns of Alsemberg, Beersel proper, Dworp, Huizingen and Lot. On 1 January 2006 Beersel had a total population of 23,433. The total area is 30.01 km² which gives a population density of 781 inhabitants per km². It is close to Brussels; Beersel is approximately 12 km southwest of the center of the city.
Beersel is perhaps best known for the "Kasteel van Beersel" (Beersel Castle), built between 1300 and 1310 by Jan II, the Duke of Brabant, as a defense for Brussels. Guillaume Dufay (1397–1474), the most famous European composer of the 15th century, was most likely born in Beersel.
Beersel is known for its boterham met plattekaas en radijzen (sandwich with white cheese and radishes), usually served with a geuze beer, and for its mandjeskaas (literally 'basket cheese'), which is a white cheese stored in little baskets. Beersel also has two traditional, authentic geuze breweries, Oud Beersel and 3 Fonteinen.