Square Louis XVI is where King Louis XVI and his wife Marie Antoinette were initially buried in a mass grave after their execution by guillotine at the Place de la Concorde (their remains were later transferred to the royal basilica of Saint Denis in 1815). It is also where the Chapelle Expiatoire is located, which was erected in their memory. It is the only public place in Paris bearing Louis XVI's name. However, despite its grisly history, Square Louis XVI is now a beautiful spot of greenery in the 8th arrondissement.
