In the Opera House, the drawbridge is located in a wooden room with wooden platforms and Falling Sandbags and Glass Shards. There Lara must first drop the Falling Sandbags down so she can move safely around in the room. Then Lara must climb higher to an alcove in the wall with a switch. Flipping the switch lowers the drawbridge, which makes it possible to progress further in the level.
In Tibetan Foothills the Drawbridge is located in a snowy area with a frozen small pond of water. Lara must first find the Drawbridge Key, which is used in the lock right below the Drawbridge. Using the key lowers the bridge, making it possible to move with the Snowmobile to the other side of the area. The Drawbridge doesn't stay up very long, as soon as Lara has gone over it and continued a bit away from the area, great rumbling and tumbling is heard as a large avalanche sweeps the frozen lake. This lowers the bridge, but there's no need to use it again.