Andrew Marr climbs crane building London's Shard
2 June 2011 Last updated at 06:34 BST
Andrew Marr has climbed one of the cranes building the Shard skyscraper in London to meet its operator, who said he "never tired of the view".
When finished the Shard will tower 1,016ft (309.67m) above London. As floors are constructed, the crane also has to keep growing taller than the building for work to continue.
Operator John Young said he often worked "blind", as he could not see the steel he was moving hundreds of feet below.
Andrew Marr's Megacities looks at how people live in five of the world's biggest cities - London, Dhaka, Tokyo, Mexico City and Shanghai. The first programme Living in the City can be seen on BBC One at 2000 BST on Thursday 2 June 2011 and afterwards on BBC iPlayer.