President Felipe Calderon inaugurates the Baluarte bridge in northern Mexico, which at 402m is now the tallest bridge in the world.

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Mexico inaugurates tallest bridge

US teenager Jordan Romero becomes the youngest person to climb to the summit of the tallest mountains on each of the seven continents.

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US teenager sets climbing record

Scientists in America are using an industrial crane to study the life cycle of some of their tallest trees.

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Studying America’s tallest trees