The Fonte do Ídolo, Quintal do Ídolo, Ídolo dos Granginhos rock sanctuary, or Idro, as it was locally known for, is located at Braga's downtown, in the Rua do Maio street.
The large granitic outcrop has a NE - SW orientation and is carved with inscriptions and high relief (embossed?) figurines carved through a rough 3m space, distributed by two big sets. A 5m by 10m reservoir can also be found in this space along with steps carved in the outcrop. The construction of this rock sanctuary can be chronologically framed in the 1st century AD.
The first sculpted set is located on the left side of the outcrop and is characterized by the presence of a standing figure wearing a gown/robe but having its face highly eroded. It holds in its hand what has been interpreted as a vase or a cornucopia. This set also displays the following text: [CEL]/ICVS FRONTO/ ARCOBRIGENSiS/ AMBIMOGIDVS/ FECIT.
On the right, second set, you can find a 60cm long by 50cm wide aedicula, displaying a bust, with male characteristics, on its inside.
This bust is elevated by a pediment (?), decorated with a dove and a hammer. At its base is the water spring that runs by a dug groove towards the outside of the reservoir. This set also displays text associated to this structure: above its frame: CELIUS/FECIT, on the pediment(?); TONGOE/ NABIAGOI, and at the base: FRONT.
The archaeological interventions began during the 1930s, which allowed the recovery of large quantities of Roman construction material (clay tiles and imbrex), along with a granite slab with approximately 0.50m tall and 0.15m wide, bearing the inscription NABIAE / RVFINA / VSLM. Archaeologist Carlos Teixeira was led by this discovery, to link this place with the Nabia deity.
The surrounding area of Fonte do Ídolo was heavily disturbed during the late 1980s, close to the Hospital in Rua dos Granjinhos, with a wall being identified in one of the cuts (?).
Several archaeological works were carried out by the Office for Archaeology of Câmara Municipal de Braga during 1993 and 1994, allowing the identification of Roman plumbing and reservoirs on the northern area of the sanctuary, possibly fed by the Fonte do Ídolo. South of this spot, foundations of a wall were also found having the same chronology. The follow up works carried in 2003 by Francisco Sande Lemos and José Freitas Leite, part of the monument's enhancement program, allowed the discovery of a pavement dated from the Late Antiquity, which was not disturbed(?), as well as a Roman water conduit, fed by the fountain, to the south.
Epigraphic, functional, and symbolic interpretations of this space have been quite diversified since its inception. For Sande Lemos, this space can be interpreted as a private sanctum, integrated in a garden space of a dwelling on the outskirts of Bracara Augusta. Manuela Martins considers, however, that the Fonte do Ídolo could be a public monument, built by Celicus Fronto (LEMOS, 2006).
Despite the difference of interpretations, agreement is made regarding this space being a sanctuary dedicated to an aquatic divinity.