The vast open pit at Mina de São Domingos is one of the most striking industrial landscapes in Portugal. Romans worked this hillside for four centuries; by the time the British arrived in the mid-19th century they were extracting copper pyrite on an industrial scale, running their own narrow-gauge railway down to a riverport at Pomarão where steamships loaded the ore for Huelva. The pit they left behind is immense — hundreds of metres across, terraced in bands of ochre, rust, and purple — and the lake that has filled the bottom is a vivid, unnatural red from the acidic iron-rich water.
Walk the rim of the pit early in the morning when the light is low and the colours are at their most intense. The views are extraordinary in a desolate way — the scrub plain of the Alentejo stretches to the horizon and nothing moves. Allow at least an hour here, and combine it with the village ruins and the Cornish cemetery nearby.