For me, [in my headcanon, the Doctor’s explanation about the Towers] was just the Doctor, in his faltering way, trying to open up on the subject of emotion and accidentally lecturing on an acoustic effect in a nearby tourist attraction. Which of us hasn’t made that mistake for a date?
But, yes, that episode is all about River and the Doctor, both asking and answering the big question about who they are to each other. And look, since it’s my sacred duty to invite scorn and derision once a month in the writing on this column, I’m going to admit I’m rather proud of some of the scenes in that episode–especially River Realises and Twenty Four Years. Yeah, help yourselves, blast away. But I’m hardly ever proud of anything I write (“Quite Right,” the millions cry), so I’m saying it anyway. Nyer!
— Steven Moffat on River and the Doctor in THORS (DWM 496)