What is the greatest advance in construction?

Designers, builders and engineers have that instinctive desire to construct longer, higher, deeper, cheaper, quicker, more chaotic or more elegant. But what single item or concept has nurtured the greatest advance in construction?
NCE and sister titles The Architect's Journal and Construction News in association with Corus Advance, is producing a compilation of the construction industry's greatest hits from the last couple of millennia. Our aim is to draw together all the things – the theories, methods, materials and machines - which have driven the industry forward.

We've already asked some of the biggest names in construction what they think and have printed a selection this week. The rest will be rolled out between now and the New Year. In the meantime, we need readers to scrutinise these nominations and fill in the gaps to help us create a shortlist. From this, a public vote with help decide which is the greatest.

So let the squabbling begin – is it CAD or the calculator; silicone sealant or steel girders - or something completely different? 

Make it be known and send us your nomination with a brief explanation to advance@emap.com or Corus Greatest Advance, New Civil Engineer, 1st Floor, Greater London House Hampstead Road, London, NW1 7EJ

There is no strict timescale within which the Advance should have taken place, but should be something which has been realised in recent memory.