Alter Pedroso

The ruined castle occupies an elliptical area set along a north–south axis, with its longest measure about 86 metres and its shorter axis roughly 50 metres. The hill rises to about 420.9 metres above sea level and the surviving built elements cling to rocky slopes and outcrops. The defensive lines were constructed in local stone and in places the walls tie directly into the bedrock, producing a stitched appearance where masonry meets rock.

Surviving sections of curtain wall include the exposed base of a west wall extending some 13.5 metres, and a 3.3-metre fragment on the north side that is attached to the rock. To the east a short wall links into bedrock. On the south and southeast there are two roughly parallel wall traces, each about 1.6 metres wide and between 6.2 and 10.5 metres long, which meet at an obtuse angle and conclude at a corbel measuring about 2.9 metres. Foundations of a south wall run approximately 16 metres from the cemetery to a corbel. A pointed, ogive gate survives on the southern side, framed by granite jambs measuring between 1.9 and 2.4 metres, and a short, perpendicular wall projects northwest from that opening. A Gothic-style portal is among the earliest dressed elements still visible.

Within the former courtyard a geodesic survey marker sits at an elevation of 412.83 metres, while the hilltop reaches 420.9 metres. Modern interventions occupy parts of the site: a lookout and a municipal water reservoir lie to the southeast, and a firefighters’ observation post is positioned in the lower sweep of the slopes. In 1940 masonry from the southwest defensive line was removed and reused for road construction, a reuse that altered the plan and left many wall segments fragmentary.

Directly below and just west of the castle the remains of the Hermitage of São Bento stand in ruin but retain identifiable architectural elements. The chapel follows a simple longitudinal plan, with a nave measuring about 4.0 by 4.9 metres and a chancel approximately 2.15 by 4.10 metres. A triumphal rounded arch separates these spaces, and a vestigial niche about 0.47 metres in size can be seen. The hermitage complex contains a small west–east atrium of roughly 4.75 by 3.40 metres that provides access to the doorway and the adjacent cemetery; a bell structure is attached above this entrance. The chapel doorway itself survives as a distinct element.

Construction details in the hermitage include a portico formed with a chamfered arch set in tile masonry and internal divisions expressed as thirteen compartments with wall thicknesses nearing 0.50 metres. To the east of the castle a small cistern about 1.9 metres deep is recorded south of the lookout. Overall the site presents a patchwork of foundations, corbels, wall fragments and the hermitage ruins, with later municipal features and nineteenth- and twentieth-century interventions evident in the present landscape.