🇵🇹 Portugal · Megalith
Antas de Olival da Pega
Early Neolithic – Chalcolithic (c.3500–2800 BCE) · Alentejo Megalithic (Almendres tradition)
Reguengos twin antas in shared mound — Anta 1 with 16 m corridor, 4 m polygonal chamber and schist plaques (3500 BCE).