Casa dos Ottoni is Serro's most useful museum stop, a low eighteenth-century house tied to one of the region's prominent families. The rooms cover the town's history, religious art, household objects, documents, and the culture around Serro cheese.
It is not a large museum, but it gives context to the town before you start climbing between churches. The address on Praca Cristiano Ottoni also puts it in the lower part of the old centre, where Serro's slopes begin to show their teeth.