The history of bridges is almost as old as the history of urbanism. King Nabopolassar supposedly built the first bridge over the River Euphrates connecting the two halves of the city of Babylon. Prior to that, people had to be ferried across the river.
While the bridge in Babylon indeed brought the two halves together, the term ‘bridging the gap’ in the normal usage too has come to imply an act of bringing two parts together. And in older cities like London and Rome, built along the two banks of the rivers Thames and Tiber respectively, the multitude of bridges help to ‘stitch’ the city together. In the central stretch of the River Thames as it crosses central London, starting from the Vauxhall Bridge in the west till the Tower Bridge in the east, over a distance of five kilometres, more than 10 bridges ‘stitch’ the north and the south side of the city together.