Napoleon III, since the Crimean War Britain's closest ally, visited London in April 1855, and from 17 to 28 August the same year Victoria and Albert returned the visit. Napoleon III met the couple at Boulogne and accompanied them to Paris. They visited the Napoleon I's tomb at Les Invalides (to which his remains had only been returned in 1840).
Source: Wikipedia
The construction of the Hotel des Invalides was initiated by Louis XIV in 1670. Its original purpose was to serve as a hospital and a retirement home for war veterans. Located in the 7th arrondissement of Paris, the complex of buildings includes museums and monuments relating to the military history of France.
Some of France’s war heroes were buried in the Dôme des Invalides, a large church in the center of the complex. The most notable tomb is that of Napoleon Bonaparte whose remains were brought from Saint Helena to France in 1840.