El Año de los Tiros Historical milestone · Minas de Riotinto, Cuenca Minera, Huelva On 4 February 1888 the Civil Guard opened fire on a demonstration of miners and residents protesting in the town square against the pollution from open-air ore-roasting heaps (teleras), causing numerous deaths. 4 de febrero de 1888 Photo: Geom (CC BY-SA 4.0) What to see and do in Minas de Riotinto