Fair of Otoño de Monzón Activity · Monzón, Cinca Medio, Huesca Image of Monzón, not of the place itself. The Feria de Otoño de Monzón continues the festival of San Mateo, on 21 September, which has its origin in a medieval fair of horses, livestock and farm produce held on that same date, when summer was ending. Photo: Zarateman (CC0) What to see and do in Monzón