Tower Bridge

I've been working on a Lego set over the last week, and I finally finished constructing it yesterday:

I don't think the photo does justice to just how huge this bridge is.  It's about 40'' long and 18'' high, and currently sits on top of 2 bookcases because that's about the only place big enough for me to put it.  Not a particularly challenging build, and a bit too much repetition, but it does looks pretty good.  I've also got a Lego Big Ben set that is apparently on the same scale as Tower Bridge here - though I don't have the room to put that anywhere just now.  I have built this bridge before - so I was a bit alarmed by the number of spare pieces I had left behind once I completed it.  I'm sure that probably means that I've missed a step somewhere, but for the life of me I can't see anything wrong with the finished product.  And there's no chance now that I'm going to take it apart and put it together one more time...