It was strategically vital as an outpost of the 'Linha de Defesa' during the frequent border conflicts between the kingdoms of Portugal and Castile.
The masonry used in its construction consists largely of local quartzite, which is highly resistant to weathering.
The castle served as the seat of the Municipality of Alegrete from 1267 until it was integrated into Portalegre in 1855.
Excavations in the area have uncovered medieval pottery shards that suggest continuous, albeit low-density, occupation from the 13th through the 17th centuries.
Its height above sea level exceeds 800 meters, making it one of the highest castle sites in the Alentejo region.
The Castle of Alegrete is a medieval fortification situated at the highest point of the Serra de São Mamede, overlooking the border between Portugal and Spain. Originally built in the 13th century to reinforce the defense of the Alentejo frontier, it underwent significant reconstruction during the reign of King Dinis. The site features an irregular polygonal plan characterized by thick stone masonry walls and a surviving keep tower. Its strategic positioning provides an unobstructed view of the surrounding landscape, extending toward the plains of Extremadura. The structure remains a prime example of Gothic military architecture adapted to a mountainous topography. Most of the original living quarters have collapsed, leaving the remaining perimeter walls and the keep as the primary focal points of the site. Access to the interior is gained through remnants of the original gates. The ruins are maintained as a historical heritage site accessible to the public for exploration.
The top of the stairs leading to the keep, which offers a panoramic vista of the Serra de São Mamede mountains.
Wear sturdy, closed-toe hiking boots, as the terrain within the walls is uneven, rocky, and potentially slippery.
Bring windproof layers, as the elevated mountain location creates significantly colder temperatures and higher winds than the surrounding plains.
Ensure your phone or camera is fully charged, as there are no charging facilities and the climb can be physically demanding.
Do not attempt to reach the castle in severe weather or high-wind conditions, as the exposed paths become hazardous.
No formal dress code, but appropriate outdoor footwear is essential; maintain respect for the integrity of the ruins by not climbing on unsupported masonry.
