This paper examines the length of stay of cultural tourists in a mountain destination in the northeast of Italy. A microeconomic perspective of cultural tourism is provided, in which the main point of interest is to analyse the attitudes of visitors regarding culture and their overall vacation. To this end, visitors' behaviour is examined through survey data obtained at the South Tyrol Museum of Archaeology in Bolzano, Italy. A zero-truncated negative binomial model is empirically estimated, unlike in other studies, as a generalization of a Poisson distribution. The analysis identifies the main determinants that influence the length of stay of cultural tourists: nationality, age, employment, income, costs associated with the journey – all have an impact on the length of stay. Specifically, variations in these factors correspond to variations in the duration of the vacation. The duration is also positively affected by the presence of the icemen Ötzi in the museum and of other cultural attractions. The findings provide an essential tool for managing heritage resources and planning future tourism developments around the Ötzi museum.