St. Louis Square, often known as Carré St-Louis (though this is, to the surprise of many, actually an anglicism), is one of Montreal’s greatest public spaces. A traditional Victorian park, ringed by beautiful old greystone rowhouses and villas, it first came into existence as a reservoir in 1851. In 1880, the reservoir was drained and the square as we now know it was built, complete with walking paths and a fountain.
Except that wasn’t entirely the case. The beautiful fountain that now stands in the middle of the square, serving as a central focus for all of its activity, once found itself in the middle of a much larger basin of water. In one newspaper illustration from 1902, the basin appears to cover the entire central section of the park. It has been converted into a summer wading pool for children, who frolic in the water as their mothers, dressed in long dark frocks, promenade around the square under the shade of parasols.
I’m not sure when the basin was redeveloped, but it continued to exist as recently as 1943, according to one photo showing workers improving the basin’s drainage system.