After lowering the water level and using the pull chain to open the door, as shown in the previous section, go through that door.

Follow the tunnel to a raised crawlspace.

Crawl through and drop down in the next room.

In a short cutscene, the 2 undead knights Von Croy/Seth animated now come after Lara. These ancient enemies cannot be destroyed, so they don't count as "kills." They can, however, be used to open the exit.

There are no pick-ups here, but if you decide to explore anyway, watch out for the deep pits in the middle and northeast corner of the room.

To reach the exit, immediately after the cutscene finishes, side flip to the left.

Roll and run up the ramp along the right wall.

The knights follow but slowly, moaning and groaning as they come. (You'd be stiff and achy too if you'd been dead for centuries.)

Continue around the corner to the left and up the next ramp.

When you reach the top, position Lara in front of the petrified wooden barrier nailed across the exit.

Wait for the knights to come up the ramp. If you like, you can turn around and watch for them, but once they get close, roll and step forward...

...so Lara is right up against the barrier and ready to move.

When they swing their swords at Lara, they'll break the beams.

Run forward and quickly pull up into the room above.

[Citadel Walkthrough]