City of Paris Opens Its Sewers to Public Tours During the 1867 World's Fair
ESTIMATED73% CONFIDENCEThe Paris[3] sewer museum's own history page states tours "began in 1867, during the World's Fair" without naming an exact day, so the pin uses the Fair's opening date.
During the 1867 Exposition Universelle, Paris opened Baron Haussmann's newly rebuilt sewer network to public tours for the first time, turning Eugène Belgrand's engineering into a civic showcase.
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