I went past it on the train a few weeks ago. Huge thing.

The comment about minor errors/miscalculations reminded me of the Hubble Telescope.

You will probably find that the structure is not especially rigid, structural engineers have found that rigid structures don't cope too well with high winds, so they build in flexibility. Modern skyscrapers move about 1 metre in any direction at the top when it is windy, although I appreciate this is not quite that large and not such a wind barrier.