^ It's part of the guest area... However what it will all look like is very much a question mark. We only really know what Diagon and Knockturn will look like.
And here is my question and answer picture. What is that thing they are building in the middle of what should be a street? The pink lines are showing what steel work has yet to be started. It hit me while doing this that the service road will go right under the load station of the HE. Ain't that something!