After living in this magnificent city for 25 years I like to think that I have explored its many nooks and crannies, and discovered all of its secret corners. So when the founder of a newly launched interactive game, Hidden City, assured me that it would show me a completely new side of the capital, I was sceptical to say the least. However, the challenge appealed to my competitive side, a surefire way to guarantee my cooperation, and so I set off, dragging my boyfriend behind me.