A pretty awesome map of Miami showing all the early plots divided up and it has to be after 1910 because that’s the year the Miami Herald was formed, and they have a plot in their name on the top right area of the map. So this is probably in the 1910s or 1920s. The Miami River is on the left and the mouth of the river would be slightly off frame on the bottom left corner. The Royal Palm Hotel location on the center/bottom (south) area of the map. And Avenue D was one of the main arteries back then, which is present day Miami Avenue and even back then had a bridge to cross the river into the Brickell side.
And what’s cool about this is that if its true, X marks the spot of where the city of Miami was incorporated. RIght on Avenue D on land owned by Coast Steamship, Co. Photo of the reported building can be seen below courtesy of Wikipedia. Click on the map to enlarge.
And another old Miami map from the same angle. But this one shows where the Old Fort Dallas used to be….