I scrounged around for a good photo of Big Ben and found this on Flickr:

It's a neat angle and I liked the clouds, but I wanted the shot to more closely resemble the night scene from the movie where the kids and Peter all land on one of the arms. So I threw a bluish-purple layer over it set to Overlay (which happens to be one of the colors for our wedding):

Now the hue is correct, but that sky is way too bright to be a night shot. I went in and adjusted the curves to darken everything up (but kept the clock face relatively light since Big Ben lights up in the evenings):

Next came a little bit of lighting on the face.

I wanted the focus of the picture to be on the tower itself, so I found a photo I'd shot a while back of some clouds, chopped out a piece and covered up the part of the building I didn't want in there.

Lastly... a little fairy dust to add to the magic. :) I've got a Photoshop brush that I'd made a while back that does some nice sparkly effects!

It's nothing too fancy, but I think it'll look nice with a good font and a catchy phrase. Maybe "Think of a Wonderful Thought?"