Sacré-Cœur is built of a stone that cleans itself every time it rains: the travertine reacts with rainwater and releases calcite, a white mineral that keeps sealing the surface. The basilica crowns Montmartre, the highest natural point in Paris, and was raised over four decades by public subscription after the hard years of 1870 and 1871 — funded coin by coin rather than by the state. Paul Abadie won the commission with a Romano-Byzantine scheme of pale domes, closer in spirit to Istanbul or Venice than to Gothic Paris and deliberately unlike anything else on the skyline. Work began in 1875, slowed by foundations that had to be sunk deep into the soft gypsum hill, and the church was only consecrated in 1919, once the First World War had passed.
You climb to reach it, up terraced steps and gardens where the city falls away behind you, or by the small funicular that spares the legs. From the forecourt the whole of Paris spreads flat and grey-gold below. Inside, the eye lifts to an immense golden mosaic of Christ filling the apse, and to a hush that rarely breaks. Today the steps are a gathering place at dusk — buskers and students among the pilgrims — while the dome stays the second-highest viewpoint in the city.