A drawbridge is a bridge with a section that can be raised or lowered. In medieval castles, drawbridges crossed the moat (a water-filled ditch surrounding the castle). During peacetime, the bridge stayed down so people could walk across. When enemies approached, soldiers raised the drawbridge using chains and pulleys, creating a barrier that protected the castle entrance.

Modern drawbridges work similarly but for different reasons. Cities with busy harbors use drawbridges to let tall ships pass underneath. When a ship needs to go through, the bridge operator raises part of the roadway, stopping car traffic temporarily. Once the ship passes, the bridge lowers back down. Chicago and Florida have many drawbridges because of their waterways.

Some modern drawbridges split in the middle and lift both sides, while others tilt up from one end like a seesaw. Tower Bridge in London is one of the world's most famous drawbridges, combining Victorian engineering with medieval castle style.