Historic hilltop walled medieval village of Mertola with castle, on the banks of the river Rio Guadiana, Baixo Alentejo, Portugal, Europe

Barragem do Alqueva, Rio Guadiana river, Alqueva dam hydroelectric power, Moura, Portugal, Europe

Historic hilltop walled medieval village of Mertola with castle, on the banks of the river Rio Guadiana, Baixo Alentejo, Portugal, Europe

Barragem do Alqueva, Rio Guadiana river, Alqueva dam hydroelectric power, Moura, Portugal, Europe

Barragem do Alqueva, Rio Guadiana river, Alqueva dam hydroelectric power, Moura, Portugal, Europe

Barragem do Alqueva dam, part of the multipurpose water management project on the Rio Guadiana river, hydro-electricity generation electricity power lines, Moura, Portugal, Europe

View over whitewashed village of Alcoutim on Rio Guadiana river, Alcoutim, Algarve, Portugal, Europe

Windmill above village and Rio Guadiana river with view to Portugal, Sanlucar de Guadiana, Huelva Province, Andalucia, Spain, Europe

View from castle across Rio Guadiana towards Spain, Alcoutim, Algarve, Portugal

Ferry on the Rio Guadiana border river between Portugal, Vila Real de Santo Antonio, Algarve, and Spain, Ayamonte, Andalusia, Europe

Black headed gull (Chroicocephalus ridibundus) bathing at sunrise, Rio Guadiana, Fernan Caballero, Spain