Poised at the apex of the hill like a grande dame in crinolines, this odd-looking 19th-century basilica has become one of the city’s most famous landmarks. After France’s defeat in the Franco-Prussian War, prominent Catholics vowed to build a church consecrated to the Sacred Heart of Christ as a way of making up for whatever sins the French may have committed that had made God so angry at them. Since 1885, prayers for humanity have been continually chanted here (the church is a pilgrimage site, so dress and behave accordingly). This multi-domed confection was inspired by the Byzantine churches of Turkey and Italy. Construction began in 1875, and the church was completed in 1914, though it wasn’t consecrated until 1919 because of World War I. The white stone was chosen for its self-cleaning capabilities: When it rains, it secretes a chalky substance that acts as a fresh coat of paint. The interior of the church includes a breathtaking mosaic ceiling, installed in the 1920s. Most visitors climb the 300 stairs to the dome, where the splendid view of the city extends over 48km (30 miles).