The Castelo de Arnóia (also known as Castelo de Moreira and Castelo dos Mouros), located between Arnóia and Moreira, in the municipality of Celorico de Basto, is classified as a National Monument since 1946 and is owned by the State.

It was an important castle head of land, already mentioned in the inquiries of 1258 and its construction is part of the movement of fortification that marked the European territory between the 10th and 12th centuries. The Castle of Arnóia is part of the Romanesque Route.