After solving the PLANETARIUM puzzle and briefly entering the FIRE CIRCLE ROOM, as shown in the previous section, you'll emerge in the MAIN HALL through the door in the lower level, northeast corner (i.e., door C in the diagram). Go around to the right...
...and push open the left door on the lower level, north side of the MAIN HALL.
Follow the hallway and break the ceramic jar to get the small medipack and Uzi ammo inside.
Continue to a room with a stone pedestal, banners hanging from the ceiling, and an elaborate golden circle inscribed on the floor. When you step down onto the floor, 2 mechanical men emerge from the side alcoves.
Avoid them while shooting the blue gems in their chests to defeat them, just like you did the others. You may want to back down the hall while shooting...
...then jump past the enemies, roll...
...and continue firing as you back up into the pedestal room.
- OR -
Instead, step down into the room then immediately roll and run back the way you came.
Run back down the hallway to the corner just before the blue door leading back into the MAIN HALL.
The mechanical men will follow...
...but they won't pursue Lara any farther than this, so you can take your time shooting them with pistols.
When the coast is clear, approach the pedestal in the room with the hanging banners and press Action to take the FIRE CIRCLE SCROLL. Open your inventory to examine it for a clue: "For the serpents to live, all must first be stilled. Provoke each in turn, and the circle will burn complete." Return to the MAIN HALL the way you came.