Portalada de Carlos III Monument · Riotuerto, Trasmiera, Cantabria Monumental gateway (portalada) from 1784 in the La Cavada district, a Bien de Interés Cultural linked to the historic Real Fábrica de Artillería (Royal Artillery Foundry). 1784 Photo: Valdavia (CC BY-SA 4.0) What to see and do in Riotuerto