Boy, that sure doesn’t look like a ‘sketch’. Doesn’t look like a painting either, looks like someone did a model of the fort and then photographed the model.
Was the artist from 1731? Why is it he knew this fort’s layout so well but we at this point are excavating the foundations?
I suppose the artist could be that good, would like to know if this is indeed a painting.
Maybe it was a miniature used in a movie. :’)