What do you mean one photo? last I knew an HDR image was 3 pictures taken at 3 different exposures. all framed the same and usually shot on a tripod. I guess you could edit the exact same one if you shot it in RAW? dont know why. like I said last I knew it takes at least 3 different pictures.
as far as the HDR goes I feel like there might be more detail to be had in the sky? maybe it was just a clear sky day. for future ones days with clouds look AMAZING when done correctly. Building and statue looks good tho!