I took these few pictures today (Monday) of the various street-levels that I was talking about before. Here is the view on George IV Bridge looking north towards the High Street/Royal Mile. Candlemaker Row goes down towards the Cowgate and Grassmarket on the left.
A bit farther north on George IV Bridge, looking southeast back down the road, and at the “intersection” with the Cowgate, signified by the gap in the buildings on the left side of the picture.
Here are two such overpasses viewed from the Cowgate. On the Left, George IV Bridge seen from the Cowgate, on the right, Nicholson/South Bridge as viewed from the Cowgate.