Here's a dynamic page, where Nightwing swings past Big Ben:
The first time I read this comic, I don't think I paid much attention to it. Looking at it again, though, it raises a few questions. For instance, what is his rope attached to? Here's a photo of Westminster, taken from the other side of the Thames:
The clock tower is clearly the highest point around, but his cable appears to be attached to something higher. I remember a similar issue in an old Spider-Man comic, where he was shown swinging above the Empire State Building; the letters page said something like "Er, would you believe that Stan the Man was flying past in his helicopter, and gave Spidey a lift?"
The second question is where Nightwing started his swing; how did he get into the position shown in that picture? He's heading north, so presumably he's just crossed the river, but the bridge is pretty low. For that matter, even if he'd started south of the river with a really long cable, the buildings there aren't particularly high. So, it looks as though the helicopter theory may be the only explanation here, implying that he's being dragged through the air behind it.
This doesn't really matter in the great scheme of things, but it serves as a useful reminder to me in my future drawing: rather than going for a generically cool image, it's better to have something that makes sense.