The hermitage of Our Lady of Arboló is located close to the old partition between the municipalities of Arcalis and Gerri de la Sal. It stands on the upper part of a rocky promontory that rises above the left bank of the Noguera Pallaresa river, at a point known as the Estrecho [narrow pass] of Arboló.


The church consists of a single rectangular nave, whose head is covered by a barrel vault. At its east end, there is a semicircular apse that opens into a nave with a double presbiteral arch. In the inner part there are now three doors, one in each wall. One of these doors, which has the form of a decreasing double arc, opens into the side of the chancel and provides access to the inner rooms of the sanctuary. The two other doors, which are located in the walls to the west and south respectively, each has a single arc. The western door, which was built a little later, has three diminishing arcs. A smooth impost that flanks the whole of the facade can be seen 1.5 m above the arc of the vestibule and extends for about two meters along each of the lateral walls. The impost continues along the south wall, but continues for about 80 cm more than along the the western facade. This ornamental element is not frequent in religious buildings of this area, and this confirms that it was probably added at a later date.


Crowning the facade there is a small bell tower with a square base. One of the singularities of Arboló is, without doubt, the perfect disposition of the ashlars; their chromatic selection makes us think of an advanced period within the Lombard Romanesque tradition, with a chronology towards the end of the 12th or beginning of the 13th century.