While he was rebuilding the boulevards of Paris, Haussmann simultaneously rebuilt the dense labyrinth of pipes, sewers and tunnels under the streets which provided Parisians with basic services. Haussmann wrote in his mémoires: "The underground galleries are an organ of the great city, functioning like an organ of the human body, without seeing the light of day; clean and fresh water, light and heat circulate like the various fluids whose movement and maintenance serves the life of the body; the secretions are taken away mysteriously and don't disturb the good functioning of the city and without spoiling its beautiful exterior."