In April 2011, my family and I visited the counties of Surrey and Hampshire, the former of which borders London. I then visited London in June 2012, and, as I wrote about recently, I went to London again in March 2013. On only one of those occasions did I spot the iconic and infamous 30 St Mary Axe ("The Gherkin"), and on none did I see The Shard; furthermore, I never saw 30 St Mary Axe on the two times I was in the city: I glimpsed it for about two seconds when we were on the motorway to Surrey.
Why is this notable? Well, because both buildings help define the London skyline: 30 St Mary Axe because of its unique shape and The Shard because it is the tallest building in the United Kingdom and the second-tallest in Europe. Despite their highlights, I missed spotting these two prominent towers...and on my recent visit I was actively looking out for them, too, but my view was obscured by other structures. Seriously, I missed them both!
I am an admirer of both towers; I'll have to have another go at spotting them on my next trip to London!