The first bridges were pieces of wood that someone placed across a stream. These bridges were not very strong. If too many people tried to cross at one time, the bridges broke and people feel into the water!
Later people made bridge of stone. The Romans made some very good bridges of stone and many of these are still standing today. Sometimes, however, no one could build a bridge across a river which was too wide and too deep and the water was too strong.
About two hundred years ago, a man named Darby built the first iron bridge. It crossed the River Severn in England. It was very strong and cars and trucks still used it today. Bridge builders then began to use iron and steel to make two kinds of bridges. The first kind is the suspension bridge.
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