Réaumur – Sébastopol is a station of the Paris Métro in the 2nd arrondissement of Paris. It serves Line 3 and Line 4. The station was opened as Rue Saint-Denis on 19 October 1904 as part of the first section of the line 3 between Père Lachaise and Villiers. It was renamed to the current name in 15 October 1907. The line 4 platforms were opened on 21 April 1908 as part of the first section of the line from Châtelet to Porte de Clignancourt. It is named after the streets of Rue Réaumur and the Boulevard de Sébastopol, which are named after the scientist René-Antoine Ferchault de Réaumur and for the port of Sevastopol in Ukraine, the scene of the Siege of Sevastopol (1854–1855) during the Crimean War.