Actually, Wembley had been pencilled in for this year's final but Uefa didn't think it would be ready in time, so the chose Moscow.
To be honest, they probably should have two or three stadiums on standby and take a decision when they know the Semi-Final line-up.
It is ridiculous to be shipping 40,000 fans or so all the way to Moscow. Apparently there will be lots of empty seats as people have decided to watch it at home.