Built at the behest of Napoleon III to honor a prostitute whose well provided water to Pondicherry for many years.
There are many versions of the story. The gist of the one I read is that this lady-of-the-evening was stunningly gorgeous and — as a result of all her customers and shrewd financial planning — she was rich. When the King came by he was angry that she had a nicer house than him, and so he had it burnt down. However, by volunteering to build a well of unparalleled output and hygiene for the people of the area, she put the King in a rough spot in which he could neither have her executed nor force her into his harem.