In earlier centuries, in addition to wars and local disasters (fires), epidemics in particular caused great losses among the population.
For example, the plague epidemic in Oggau from 5 August to 12 December 1713 claimed 95 victims, more than 10% of the population at that time. On the basis of a public vow, the municipality built the chapel in honour of the plague saint Rosalia on a hill outside the village in 1715. At the same time, the Oggau people vowed to preserve this building for all time.
One year later, the parish declared Rosalia Day (September 4th) a parish holiday, which is still celebrated today with a procession to the chapel and a solemn service. This vow of the ancestors is still kept today.