It was quite surprising to me when I learnt that we humans pack into our abdomens intestines which, if stretched out, would be as long as a double-decker bus. It was similarly surprising to me to learn that if we could stretch out all the underground and covered roads beneath the Barbican Estate, end to end, they would total 5.5 kilometres. All I was aware of was the access to car parks. But in fact there’s a whole network of roadways giving access not only to the car parks, but to the school, the Arts Centre, unloading bays for goods, and access for fire engines and ambulances and other emergency vehicles. I still struggle to believe it’s 5.5 kilometres though.