In Washington state this past week, a bridge collapsed when a truck driver's load bumped against the steel framework.

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Work has begun in Cardigan to remove the steel framework that has supported the castle walls for almost 40 years.

BBC: Cardigan Castle: Steel supports removal in ?11m work

In fact, Santiago seems like a smaller Buenos Aires, with a European style embodied in structures such as the Museo Nacional de Bellas Artes (National Museum of Fine Arts), housed within an elegant neoclassical building, and the Mercado Central (Central Market), with its filigreed steel framework imported from Britain.

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"This is a really significant event and we need to learn from it, not just in Washington but around the country, " Hersman said after taking a boat ride on the Skagit River below the dramatic scene where a truck bumped against the steel framework, collapsing the bridge and sending two vehicles and three people falling into the chilly water.

NPR: NTSB Says Wash. Bridge Collapse Is Wake-Up Call

Obama also visited with workers representing over 60 labor unions working on the site as he signed one of the final steel beams to be installed as part of the building's framework at the top of the tower.

CNN: Obama signs beam of One World Trade Center