Alison Macaulay (@alisonmacaulay)

Yes, I was going to mention Haussmann. This is part of a great series the Guardian ran a few years ago about the history of cities. https://www.theguardian.com/cities/2016/mar/31/story-cities-12-paris-baron-haussmann-france-urban-planner-napoleon - I remember being quite transfixed by the egouts (mentioned in the article), and the fact that they have an ingenious system for washing the street gutters. When I was a student in Paris many years ago, my German flatmate's boyfriend came for a weekend and they spent almost all the time underground - one day in the catacombs and the next wandering about in the sewers.