Castle of Arnoia – Celorico de Basto

The oldest known documented reference regarding the Castle of Arnoia dates back to 1064, alluding to the Castellum Celorici et oppido ibi.

This Castle falls within the military architecture of the Romanesque period, featuring elements that contribute to its insertion into this style: the keep; the existence of a single door (the multiplication of openings made the Castle’s defence more vulnerable), the underground cistern in the walled courtyard (with the aim of preserving rainwater in case of an eventual siege warfare) and, finally, the broad chemin de ronde, which defines a triangular plan.

Its construction should be understood in the light of the fortification construction movement which marked the European territory between the 10th-12th centuries with the intention of defending local populations from enemy onslaughts.

However, we cannot read the construction of this Castle in terms of territorial defence, but mainly as a landmark of a geographic area that was being reorganized: heading the Terra de Basto, a settlement named Vila de Basto was founded close to it.

However, its isolation and space limitations, which prevented the town’s expansion, may be the cause of the county seat transfer to the parish of Britelo, in 1717, which later came to be known as Celorico de Basto.

The Castle’s abandonment took place precisely from the year of county seat transfer onwards, when the elites left the small Vila de Basto and settled down in Britelo.

As synonyms of such abandonment, at the dawn of the 20th century, there were evident signs of deterioration in its interior roof voussoirs, in the damaged ashlar masonry showing multiple displacements or in its keep that had been reduced to its walls.

This situation remained until the 1930’s, when the procedures to classify this monument began. This process was only completed in 1946 with its classification as a National Monument.


10th century (2nd half) – Edification of the Castle of Arnoia, according to tradition;

1064 – First documented reference regarding the fortification;

1092 – A document mentions the properties of Celorico and Terra de Basto;

12th-13th centuries – Second occupation period of the Castle and edification of the Castle of Arnoia’s Romanesque structure ;

1717 – The parish seat is transferred from Vila de Basto to the parish of Britelo;

1726 – The Terra de Basto was by then divided into two municipalities, Celorico and Cabeceiras de Basto. The Castle of Arnoia’s keep still showed its crenellation crown;

1758 – The Castle of Arnoia was already presenting some traces of ruin;

1946 – It is classified as a National Monument by Decree no. 35,532 (Governmental Gazette no. 55, from March 15th);

1960-1963 – Period of restoration works in the Castle of Arnoia, under the responsibility of the DGEMN – Direção Geral dos Edifícios e Monumentos Nacionais [General Directorate for Buildings and National Monuments];

1985 – The Castle of Arnoia is attached to the IPPC – Instituto Português do Património Cultural [Portuguese Institute of the Cultural Patrimony];

1992 – The Castle of Arnoia’s jurisdiction is transferred to the IPPAR – Instituto Português do Património Arquitetónico [Portuguese Institute of the Architectonic Patrimony];

2002 – Archaeological surveys were carried out inside the fortification;

2004 – Installation of the Interpretative Centre of the Castle of Arnoia;

2005 – The Castle of Arnoia is reallocated to the IGESPAR – [Portuguese Institute for Management of Architectural and Archaeological Heritage];

2010 – Integration of the Castle of Arnoia in the Route of the Romanesque.

Architecture and Furniture

Featuring a triangular shield-shaped plan, the Castle of Arnoia is built on the top of a mountainous hill, with the aim of favouring the field of vision and taking advantage of the chances provided by the ground’s steep morphology for defence purposes, according to a concept of passive defence, seeking to prevent the enemy from reaching the base of its walls.

The presence of a keep and a turret are also statements of this Castle building method: the turret would allow practising flanked shooting – i.e., a shot that ran parallel to the wall line – which was critical to an effective defence of the wall base.

Therefore, Arnoia fits into the so called Romanesque castles in which defence was essentially based on the thickness and height of the walls, since their structure did not feature many solutions to provide resistance against an efficient attack in a siege situation.

The access to its interior is made through a straight-arch door, made up by voussoirs and opened on the south wall, near the keep. Nowadays, this keep stands noble and crenellated, with a look resulting from the interventions carried out in the 20th century. Closed on itself, it is torn by narrow crevices, much in a way of embrasures. The entrance opens itself up to the north, in an elevated position, with its doorsill matching the height of the chemin de ronde.

We should also highlight the existence of a cistern in the walled courtyard, a fundamental element in siege warfare, since it was intended to preserve rainwater at an underground level.

It is worth mentioning that, in general, the keeps were accessed through a wooden mobile ladder which, in the event of imminent danger, could be removed from inside the building, isolating it. Its presence tells us that, more than having as a main function to defend the local population, this Castle was designed to accommodate a small garrison.

Regular guided visits

By appointment.

Opening times


Castle of Arnoia
Lugar do Castelo, Arnoia
Celorico de Basto