In Tomb of the Ancients, you can find the 1000th lum.

1. In the room with the blocks that rise out of the water, go to the top of the ledge, but don't fall down into the next area.

2. While facing the entrance to the room (out towards the water), go to the right side, but not past the fence.

3. Jump off of the right side and helicopter down, but only helicopter to the right for about 3-5 seconds.

4. Once there, there is an indentation in the wall, go foward towards the wall and turn right. You should see a hole by the water, that
you can't see from the top ledge.

5. Fly towards the hole and continue down that path. You should enter a secret area.

6. You should see a large skull and 2 pirates will pop out of the eye sockets. Fight them and continue on the stones in the water.
Pirates will pop out of the eye sockets as you continue forward, just beat them and go on.

7. At the last stone, you should see a yellow lum in the left eye socket. Jump onto the left spider web and jump up to collect the lum.

Congratulations, you can now get all 1000 lums instead of 999. The only thing that happens is that once you get all 1000 you will have 100%. However, when playing the game, the game never registers the lum, so don't worry when you still have 999/999 at the end.