Suspension bridges are a good way to span a wide gap because they need only two support towers. These towers are usually on land or in the shallow water near the shore.

Strong cables hang between the two towers. The ends of the cables are attached to heavy anchor points on land. Small cables, called stringers, hang down and hold the deck in place.

When the Golden Gate Bridge was being designed, engineers had a lot of problems to think about.

Tall towers - The towers of a suspension bridge are usually built near the shore. One tower of the Golden Gate Bridge had to be built in the ocean. To build a base for the tower, the bridge builders needed to work underwater - 30 metres below the ocean surface. They made a huge box that reached from the surface down to the ocean floor. Then they pumped the sea water out so that they could make the concrete base for the tower.

Build it strong! - The Golden Gate Bridge is built in a dangerous place. San Francisco is near a fault line, so there is always the danger of earthquakes. In 1906, an earthquake caused huge damage to the city. Because of this, the bridge engineers used over a million tonnes of concrete to build the anchors that hold the cables in place.
Strong winds that blow in from the Pacific Ocean can make the bridge sway from side to side. Even if they reach 160 kilometres per hour, the bridge will still stand tall. Engineers built the bridge so that it could swing sideways up to 8 metres!

Gigantic cables - Another challenge was making cables strong enough to hold up the heavy deck. It weighs over 150 000 tonnes. Engineers needed cables that were over 90 centimetres thick to hold that weight. They had to make the big cables from smaller wires. It took 130 000 kilometres of wire to do the job!

There wasn't a crane big enough to lift these heavy cables, so they couldn't be made at a factory and taken to the bridge. They had to be made by machines that were right next to the bridge and then pulled across the two towers.