During fieldwork carried out on the fortification 'Benoorden Purmerend' in the Beemster, North-Holland, 49 species of land- and freshwater molluscs were recorded in the autumns of 2005 and 2007. The majority of the species are well-known from elsewhere in the vicinity of the fortification, which today is used as a winery. The find of Lehmannia valentiana under an old wine-cask was a real surprise. The presence of some natural enemies (terrestrial flatworms and shrews) and remains of the shells of the larger snail species (Cepaea and Cornu) in so-called snail-anvils were also registered.