The Park Board seems to have gotten the groundwater problem under control here, as the catchbasin is gone and the surface looks dry. This rare look at the sides and edges shows just how gigantically inappropriate this viewing platform was.
This photo is undated but, because we see the back of a thin rectangular “warning” sign, it seems like this is from the 1900s, and of a similar age as this picture.
For those readers who would like to know what that sign says, it was photographed. 