The large modernist church, reminiscent of early Christian basilicas, was built in the early 20th century. It was rebuilt in 1930, adding, among other things, a tall bell tower. It houses the Catholic parish of the Chêne-Bourg district, a residential suburb of Geneva. The church's facades are devoid of decoration and disjointedness. The only elements that break up the austerity of the walls are two small mosaics by Jacek Stryjeński, flanking the porch on the western façade. They were one of his first own works in Geneva (1949), executed in parallel with the wall painting of the church at Challes-les-Eaux in Savoy. The field to the right of the porch is filled with the tightly standing figure of the patron saint, St Francis de Sales, to the left: the figure of St Paul (below which a ribbon with the signature 'Stryjenski px / Antonietti M.' - René Antonietti was a well-known Genevan mosaic artist). A surviving sketch reveals a design for an unrealised continuation of the façade decoration: a scene of the Mourning in the tympanum and figures of angels in the side sections.

The austere expression of the basilica's interior architecture is diversified by only a few elements of the furnishings (the altar mensa, the pulpit replaced after 1950) and the large mosaics by Stryjeński centred over the apse. This, his greatest work of religious art, was created between 1950 and 1955, already without Antonietti's help. While one can find local stylistic references in the façade mosaics, especially to the Geneva mosaics of Alexandre Cingria (a leading decorator of the inter-war period, under whom the Polish artist studied in Geneva in 1943), the style of the apse decoration is definitely more archaic. Stryjeński referred here to Byzantine patterns, in keeping with the spirit of the church's architecture. The closest inspirations, e.g. with regard to the ornamental motifs used on the chancel vault, are the mosaics of the San Vitale church in Ravenna. The artist may have personally studied them while he was still serving in the army of General Władysław Anders, as well as during a tour of Italy in 1946, but this is not confirmed. On the iconographic level, too, there is a consciously realised traditionalism here: the symmetrically composed hieratic scene in the apse depicts, against a golden background, Christ throning surrounded by Mary and Saints John the Evangelist and Peter. To the right, the church's patron saint, St Francis de Sales, shown here as a bishop (a position he assumed in Geneva in 1602), pays homage to the Saviour. The figural programme is completed by the mosaics on the rainbow arch, with two archangels symmetrically placed on either side of the nave. On the right, the archangel supports a model of the local church. Below him is the signature 'JS'. Unlike the figures in the apse, the formally developed, geometrised figures of the archangels may bring to mind the pre-war works of Jacek's mother, Zofia Stryjeńska. The son of eminent Polish artists (his father was the architect Karol Stryjeński), he settled in Geneva, where his mother had already lived (the family's ties with this city, however, began in 1837, when the engineer and cartographer Aleksander Stryjeński arrived there). The solemn funeral of the prematurely deceased Jacek Stryjeński took place in this very church, and the funeral eulogy referred to the significance of the mosaic programme. The Geneva realisation is one of the most interesting examples of church mosaics in the post-war years in Switzerland; there is no parallel in Polish art of the time.