The Golden Gate Bridge has the longest single span in the world, and the tallest bridge towers. Each of the cables has a diameter of one yard, and is composed of 27 thousand wires. Foundations have been sunk to solid rock 100 feet below water. The two main cables, each a yard wide, are outlined for the entire length by electric lights-magnificent evening sight. The Golden Gate Bridge and the Oakland-Bay Bridge were under construction at the same time; the Golden Gate Bridge is considered one of the most attractive spans in the world. The wonder of the extraordinary length of the span and the way it fits in with the site, make it one of the most exhilarating of bridges.