The Roman Catholic church built on the highest point of Paris was concecrated in 1919. It is dedicated to the Sacred Heart of Jesus, but is also a political monument for the recapturing of the city during the socialist Paris Commune of 1871.
The architect Paul Abadie died shortly after the foundation had been laid and the work was finished by 5! architects (between 1884 and 1914).
The church was not to be formally dedicated until 5 years later (1919) after World War I finished.
Today the basilica is one of the most famous sights in Paris and since it is on the highest elevation of Paris it has an amazing view over the city (including the Eiffel Tower).