Brouwerij Oud Beersel is one of Belgium's most historic lambic breweries, founded in 1882 in the village of Beersel, located approximately 10 kilometres southwest of Brussels. With a history stretching back to the late nineteenth century, the brewery has long been rooted in the Pajottenland tradition of spontaneous fermentation. The brewery went through a difficult period in the 1990s but was revived and has since re-established itself as one of the last remaining authentic producers of traditional lambic-based beers in the region. Oud Beersel's portfolio is centred entirely around the classic lambic family of beer styles. The brewery produces geuze, oude geuze, and fruit lambics, all made through spontaneous fermentation using wild yeasts and bacteria native to the Senne valley. Among their flagship offerings is the Oude Geuze Vandervelden, a tribute to the brewery's heritage. The non-lambic Beersalis range is produced in collaboration with Brouwerij Huyghe. Oud Beersel is also one of only five remaining geuze blenders in Belgium, alongside 3 Fonteinen, De Cam, Hanssens, and Gueuzerie Tilquin. Visitors can explore the brewery through guided tours at the blendery and bierhuis in Beersel, where a charismatic guide brings the long history of lambic brewing to life. The brewery recently expanded its activities by taking over the Linkebeer brand, further cementing its role as a guardian of Belgian beer tradition.