Castelo de Serpa.

Perched at the highest point of the historic center, Castelo de Serpa is defined by its resilience and strategic position near the Spanish border. While much of the interior was lost to a powder magazine explosion in the 18th century, the remaining structure is notable for its massive walls and the 15th-century Torre do Relógio, one of the oldest clock towers in the country. Visitors can ascend the battlements for expansive views over the Alentejo plains or walk through the monumental Porta de Beja, framed by two imposing cylindrical towers. Within the walls, the 17th-century Palácio dos Condes de Ficalho is uniquely integrated into the fortifications, while a small archaeological museum houses artifacts ranging from the Paleolithic to the Roman era. It remains a quiet, atmospheric site that effectively anchors the town’s whitewashed labyrinth.