Imagine a squat concrete bridge striped black and caution yellow spanning the San Francisco Bay – that's what the US Navy initially had in mind. Luckily, engineer Joseph B Strauss and architects Gertrude and Irving Murrow insisted on a soaring art-deco design and International Orange paint of the 1937 Golden Gate Bridge. Cars pay a $6 toll to cross from Marin to San Francisco; pedestrians and cyclists stroll the east sidewalk for free.