Linhares was already a castellated settlement in the reign of D. Sancho I, tutoring, along with Celorico da Beira and other neighboring forts, the northern section of Serra da Estrela. At the end of the 12th century, the castle's mayors, Gonçalo and Rodrigo Mendes, came to the aid of Celorico's square, which was the target of attack by Leonese troops.

The castle that arrived until today dates from the reign of D. Dinis, monarch who donated the village to his son, Fernão Sanches, and is one of the most important Gothic forts in Beira Alta Interior. Although obeying the demanding topography of the land, and integrating numerous rocky outcrops, it is a characteristic Gothic castle, with a keep associated with the fence, responding to the notion of active defense that characterizes that period of Western military history. Planimetrically, it is organized into two uneven spaces: to the West, taking advantage of the higher top, defining an irregular triangle, the alcove is located, while the source, on a wider platform, would be the primitive settlement, defended so about.

It has two towers: the keep of rectangular plan integrated in the section separating the two enclosures and the Clock Tower, also of rectangular plan, on the E flank. There is a kind of ledge in the southern part of the citadel, zone which integrates the foundations of two square-shaped cisterns and other constructions belonging to the mayoral building. It has four doors: a first one facing south, opening to the smallest perimeter area, in a broken arch and covered with a broken cradle vault, preserving the hinges in stonework; another on the wall of the opposite side and in full arc; a third in the cloth separating the two enclosures, in a broken back arch and covered with a broken cradle vault, keeping the hinges in stonework; the Porta da Traição on the West flank, in full arc with those imposed on the ledge. Torre de Menagem: rectangular plant and lowered roof of four waters.