The livestock fairs of Porto Activity · Porto, Sanabria, Zamora Image of Porto, not of the place itself. The fairs are held on the last Saturdays of the month from May to October, and the one on 26 August is the busiest; they remain the great livestock event of a municipality of only 147 inhabitants. Photo: Estevoaei (CC BY-SA 4.0) What to see and do in Porto