On 4 May 1934, as the Institution was granted its Royal Charter, leading engineers could look back over their careers to see the extraordinary development of a whole range of promising new material technologies for building the infrastructure. The use of structural steel with riveted connections had become well established, and both bolted and site welded connections had been developed and were being tried out. Reinforced concrete construction was being widely used, and Freyssinet, having just completed the Plougastel Bridge in Brittany, had developed his prestressing system and was setting up manufacturing facilities for precast prestressed beams. The George Washington Suspension Bridge, with a mainspan of 1067 m, had just been successfully completed, showing the full benefits of high strength steel wire, and the Golden Gate Bridge, with a mainspan of 1280 m, was under construction. The world’s tallest building, the Empire State, had also recently been finished.