Briefly, London's twin constructivist towers

On the left, the ArcelorMittal Orbit tower as constructed on the 2012 Olympics site. On the right, the Tatlin Tower, as re-created in the courtyard of the Royal Academy. Two steel structures, large scale structures built at roughly the same time, both painted bright red: so do they really have anything in common?

They are not the same size but look more closely, and you can see more design principles in common - expressive curved shapes kept rigid by triangulated steelwork. Both were made with the aid of sophisticated computer modelling, although you can see how the Tatlin Tower could have been made with a bit of trial and error rather than computers. The Orbit could not have been built without 3D modelling. The exact length and angle of each length of steel tube was worked out on a computer model, so that when the site assembly team put it together, the last few pieces fitted together exactly to close the loop at the top.

As abstract expression, though, the Tatlin stands out. It's a scale model of the tower designed in 1920 by Russian architect and engineer Vladimir Tatlin, but never built. The model was made for an exhibition on Russian Constructivism, so it's not a permanent structure, but it does allow you to experience something of the optimism of the early Communist state, before it became a repressive regime. The Orbit was designed by sculptor Anish Kapoor, who has done some exceptionally successful public sculptures, for example the Cloud Gate in Chicago, or the stretched funnel he installed in Tate Modern, but this isn't convincing on the same level. Answers on an e-postcard if you can tell me what it expresses.

Notes (21 April 2012)
The Tatlin Tower has now been taken down, and there don't seem to be any plans to erect it elsewhere. It was designed by architect Jeremy Dixon who interpreted the original drawings and photographs of the small model made by Tatlin.
The Orbit is 115 metres high and when the Olympics open it will have a lift and viewing platform overlooking east London.
See also, earlier posts about the Tatlin Tower and about an early visit to the the Olympics Site.