Castro Mendi is the name given in the oldest document (1202) referring to Castelo Mendo. Although the place has known occupation since the Bronze Age and shows traces of the Roman presence, the fortified structure and the urban model that characterize Castelo Mendo, are a medieval creation designed to face the needs imposed by the Christian Reconquest in the 12th and 13th centuries: promoting the repopulation of the Muslim territories annexed to the Portuguese kingdom and to sustain territorial border disputes with the Christian kingdoms of Leon and Castile in the region of Riba-Côa.

In this square, we see the hexagonal cage pillory from 1510, when D. Manuel renewed the charter.