I have a different outlook on that ship. Have you ever seen a Pusher Tug?
In a nutshell why build a large cargo ship when you could build a single smaller super powerful tug boat that pushes around a barge like thing.
They kinda look like what you have there. A ship with a freaking huge bridge so they can see all around them easily... Typically it's not a city that's on top but ya. They usually are a bit odd looking.
The tug is at the back pushing into the cargo section in a large notch at the back. Neat huh?