It has twelve meters long and is built on a simple plan: a rectangular nave extended to the east by a flat apse, all lit by a few narrow, single-splayed windows.

It is overlooked by a small plateau known as pla de Cos, and a stony spur on top of which stands the tower of Cos.[2]

[13] On August 30, 881, Carloman II again confirmed the immunity of the abbot of Arles, named Suniefred, and his possessions, including the Cella de Cotso.

[16][17] The site of the cella is on a relatively important route at the time, connecting the Conflent, from Vinça, to Vallespir and extending from Cos towards the southern Pyrenees, either via the Notre-Dame-du-Coral hermitage, or via the Sainte-Marguerite chapel on the Col d'Ares, where there is a hospice.

The cella of Cos, like Notre-Dame-del-Coral and the chapel on the Col d'Ares, served as a refuge for travelers on this route, both pilgrims on their way to Santiago de Compostela and migrants seeking work in the region.

[9] It was probably during the second half of the 9th century that a very small place of worship (of which only the apse remains today) was built, along with a building used as a refuge for travelers.

[16][18] In the 11th century, living conditions continued to improve for the region's inhabitants, with the emergence of a cloth and fabric industry in Vallespir: weaving workshops and mills were set up, and textile plants were cultivated.

[18][19][8] The bishop of Elne, Artal III, consecrated other churches belonging to the Arles abbey at this time, in a short time: Saint-Martin de Corsavy, on October 12, 1158; Saint-Étienne d'Arles, on October 19 of the same year; Saint-Pierre de Riuferrer, on November 15, 1159; the chapel of Saint-Laurent in the parish of Coustouges, on November 22, 1159.

[9] The current portal may have been rebuilt on this occasion,[18] as was a porch added in front of the church to accommodate the large number of worshippers.

Various privileges were granted to the parish priest, including the right to report directly to the abbot of Arles, rather than to the village batlle (equivalent to mayor or bailiff).

It comprises four large farms named La Font, Puig Rodon, Manyacas and Cos, as well as several isolated dwellings, and extends as far as the village of Le Tech.

[9] The parish's territory is bounded by the Coll de Maures pass and the three rivers Coumelade, Fou and Tech.

[7] In the 13th century, a signal tower (known as the Tour de Cos) was erected atop the rocky spur overlooking the church.

[4] In the 15th and 16th centuries, the four farmhouses in the parish of Sainte-Cécile were no longer generating sufficient income for their owners, who had to pay heavy charges to the Abbey of Arles.

This was particularly the case for the inhabitants of the village of Le Tech, who had a church nearby that was better served by the ecclesiastical authorities of the parish of Prats-de-Mollo.

[23] In 1711, Jean-Pierre Trescases, a descendant of Joanoto, declared in his will that he wished to be buried in the church of Sainte-Cécile, which he referred to as the "tomb of his ancestors".

[25] After the French Revolution, the church of Sainte-Cécile was looted and burned by Spanish soldiers during the raids they carried out in the département after Napoleon's troops withdrew from Spain.

[27] In 1984, Jean Ribes described the vaulting of the Sainte-Cécile church as "completely collapsed", whereas it was "still intact at the beginning of this century", and pointed out traces of fresco on the triumphal arch, as well as a staircase to the left of the entrance leading to a gallery.

A final pre-Romanesque feature is provided by the sparse, simply splayed windows and by the location of the only doorway in the south wall of the nave.

[34] The two parts of the building are linked by a centring triumphal arch built of very fine stoneware, also bonded with abundant mortar, on which traces of the planks used to hold it together during construction remain.