Paul Abadie won the 1874 competition with a Romano-Byzantine design that pointedly rejected the dominant Gothic Revival of the period. The basilica was proposed as a national act of expiation after the French defeat in the Franco-Prussian War of 1870 and the bloody Commune of 1871. This was a political programme that its architecture quietly embodies. Construction continued until 1914, and consecration waited until 1919.
The plan is a Latin cross with a central crossing dome and four smaller subsidiary domes set over the corners of the crossing bay. The composition is explicitly Byzantine, inherited from Saint-Front in Périgueux, which Abadie had restored earlier in his career and which is itself modelled on Saint Mark’s in Venice. The five-dome massing reads as a stack of additive geometric volumes, each clear in itself and visually separable, rather than as a single integrated mass. The central dome rises to eighty-three metres and is the principal silhouette. The campanile, attached at the rear and rising deliberately taller and narrower than the central dome, breaks the strict symmetry of the composition in the manner of San Marco. The travertine cladding, quarried at Château-Landon in the Île-de-France, exudes calcite when wet and effectively self-cleans, which is why the basilica reads so unnaturally white from across the city. The arched openings and pointed cone-domes deliberately avoid Gothic vocabulary. By reaching back beyond medieval France to early Christian and Byzantine forms, Abadie placed the building outside the Catholic and Republican struggle over the ownership of Gothic.
The siting is the other half of the building’s argument. Montmartre, the hill where the Commune began, is now crowned by a monument that commemorates its suppression. This meaning is rarely discussed in tourist literature, but it is legible in the siting and the patronage. Visible from almost every elevated point in Paris, Sacré-Cœur is one of the most politically charged silhouettes in the city.