In Central London, various unsightly steel fortifications have been springing up outside important buildings like Horse Guards. (See below).
Rather than spoiling the view, they could have closed Horse Guards Road to general through traffic. This would have improved the environment for tourists, and saved a huge amount of money. It's worth noting that it's still possible to park a large van very close to the Ministry of Defence despite the new steel bollards - in fact, I've seen it done. The authorities seem to be prepared to spend large sums of money on 'security measures' that don't actually work very well because they don't prevent vehicles that could be transporting bombs from passing or even parking close to strategically important buildings. It seems that interfering with traffic flow in any way is a step too far when it comes to safeguarding national security.