Ride the motorbike down the ramp and make the jump across the deep chasm.
Begin by jumping to the raised pillar in the northern pit. Drop down and get the BLACK BEETLE from the south side of the pillar. Climb the newly raised block in the SE corner of this pit and pull the switch above (a cut scene shows a block rising in the next room, giving access to a button). Go to the west side of the pillar and jump up. At this point, Lara can jump to the opening in the west wall of the pit and explore the other two pits for some pick-ups and encounter a couple enemies (exiting eventually by a ladder on the pillar in the western pit).
Push the button on the wall in the next room to open a door down the ramp to the north. Enter it and blast a red-clad skeleton in the passageway and continue to a room with a fire pit and two other openings. Lara needs to back up into each in turn until a spike ball is released, then SPRINT out and to the side to avoid the trap. Then return to the top of each passage and pull a lever to open the sphinx door.
Inside the now-open door, let Lara begin to slide down the slope, then jump over the spikes to the landing opposite (or slide, jump and grab the monkey bars and swing over). Pull the chain and return to the room with the three deep pits. An opening has appeared in the south wall. Make a running jump/grab to it and pull the overhead lever inside. Jump back over to the central walkway and find the left gate on the north wall raised. Use the revolver with telescopic sight to shoot the brass sphere inside the alcove. The gate on the right opens. Position Lara so she can making a running jump/grab to this opening and push the lever inside. The elevator floor in the next room rises.
Ride the motorbike down the ramp to find a large deep pit. First, Lara can get Secret #1. Standing at the edge of the pit, line Lara up with the opening below in the opposite (east) wall (use the binoculars with nightvsision if you can't see it). Do one standing jump backwards, then run and jump over the pit. Hold the "jump" key down and at the last moment, hit the "action" (Ctrl) key so Lara will land inside the opening. The next part is tricky - light a flare so you can see. Slowly walk up until Lara just steps on the floor where the terra cotta tiles begin. IMMEDIATELY do standing jumps backward to the opening, holding the "action" key as if to grab the edge when Lara drops out of the opening. At the last instant (just as Lara is about to grab) release the action key so she lands flush to the wall. The spike ball should just miss her. Now climb back up and follow the passage to its end, jump and open the overhead trap door and climb into the room above. Shoot the demon hounds and pick up the Secret, a large medpak.
Exit by the hole in the floor and Lara will find herself facing a closed iron door. Return to the motorbike on the other side of the pit and ride it over the ramp on the right-hand (south side) of the pit, then back over the ramp on the north side of the pit, so that the motorbike passes over the little raised platform under the fresco. This opens the iron door, so ride back to the other side of the pit and down through the newly opened door.
The next task is to turn off the flame blowers in the tunnel so Lara can ride through. Note the symbols on the floor along the north side of the room, which correspond to symbols on the raised dais with the chains. Here's one solution: Using the column that runs along the NORTHERN side of the raised platform, fist pull the chain by the symbol which looks like a ladder. This raises a block with the corresponding symbol on the floor. Next, pull the chain by the crescent moon symbol. Finally pull the last chain in the this column (with the third symbol). Now use the blocks to get to the block in the NW corner. Pull the lever. Return to the raised platform and pull the SAME chains in the OPPOSITE ORDER (i.e., the chain with the ladder symbol will be the last of the three this time). The flame blowers will now be extinguished. If you make a mistake, the whole thing can be re-set by going through the gate on the right in the north wall and pulling the chain inside.
Now, ride the motorbike through the tunnel and push the button at the end to open the door. Bike the bike up so you can get some momentum going to make the jump ahead. Once on the other side, get off the bike and jump to the platform under the door you just entered through. On the east side is a ladder. Climb down and over to the left until Lara can back flip into an opening. Blast the skeleton and head around the corner. Use the monkey bars to swing over the fire pit. Run past the flame blowers and pull the lever at the end of the corridor. Between the 2 flame blowers is a trap door in the ceiling. Open it and climb to the room above and shoot the SAS guard. Push the lever to open a door back in the room outside.
Back outside, jump to the landing by the door on the north wall. Climb down the ladder on its north side and back flip to the opening. Stepping on the first beetle tile opens the door above. Pull the lever at the end of the short passage, then return to the ladder. Climb and back flip to the opening above. Landing on the beetle tile clears the water below.
Jump in the water below and enter the opening at the base of the north wall. In the next room swim right and into the next opening. Make a left and follow this to a place where Lara can get air. From here, continue on making two left turns and following the tunnel until you find a overhead switch to pull. If you want Secret #2, continue to explore these tunnels, heading toward the back (east) until finding an opening to climb out. Pull the lever in the dark corner (this is the first of three switches which will lead to the secret).
Exit the tunnels and turn north through another small opening leading to a room with some stairs. Swim straight ahead an up through the opening in the north wall where Lara can get some air. Pull the nearby overhead switch to open a door elsewhere. Swim back out toward the stairs. Before exiting, find the switch high in the SW corner of the room and pull it (this is the second switch to gain access to Secret #2). Swim back out to the room with the ornate columns and up through an opening in the ceiling. Follow the passage to its end and climb out. Activate the reach-in switch on the west wall. A fire wraith appears. Return by the tunnel (which is now dry) to the room with the ornate columns and swim back in to the room with the stairs. Climb out and shoot 2 SAS.
Find the switch high on the wall in the NE corner and pull it to open the iron door in the room where you left the motorbike. Now find the wall switch in the SE corner of the room and pull it to drop a rope over the center of the room. Using the rope, swing up to the alcoves on the east and west walls and push the levers. A block has been raised by the north wall, giving access to the opening you swam through earlier. Inside, climb up the chute to claim Secret #2. Return to the underwater room with the ornate columns and swim up to the opening in the ceiling. Follow the passage back and go through the open iron door to get the motorbike.
Lara now has to carefully maneuver the bike over the platforms until she can jump through the iron door. As she does, the sphinx door ahead opens.
Jump the bike into the next room and immediately turn and head left as an automatic gun fires at you. Follow the course all the way around, past two more automatic guns until you pass a block with an SAS guard. Get off the bike an take care of the guard. Go around the corner to find the first automatic gun facing safely away from you. Destroy it and proceed around the course again on foot, taking out the other two guns.
Now find 3 switches (along the north, south, and west sides the central structure). Pulling them drops a rope near the ladder on the west wall of the room. Jump to the ladder, positioning Lara in the center, and climb up near the top. Back flip and twist to grab the rope behind. Swing over and land on the catwalk with the lever. As you approach the lever, the skeleton will awaken, so dispose of it. Push the lever to open the gate on the east side of the central structure. Now, if you like, explore the other catwalks on the north and south side for some pickups.
Go through the open gate to find yourself in an elevator mechanism. Use the revolver with telescopic sight to shoot the brass sphere hanging from the ceiling high above and raise the elevator. Climb out and shoot two demon hounds. In the next room (with the raised platform) find the hole in the floor. Drop and grab the east edge of the hole, then drop and grab again and pull up into a corridor. Shoot another demon hound. Around the corner, activate the reach-in switch to open a door above. Find the BLACK BEETLE on the nearby wall and take it. Notice the torch on the beetle tile near the sphinx door. You can't take it yet, so exit the way you came in. Note the sound of a door opening as you climb out of the hole.
Back above, head around the corner to the room in the SW corner, shooting two demon hounds waiting there. Above on the east wall is the newly opened alcove. Take the TOWER KEYS from the pedestal there. Now return through the central room to the room at the east side, Drop into the hole in the floor and follow the passage to retrieve the torch. Holding the torch, jump back up to the higher level. Find the flame near where you found the KEYS and light your torch. Lara must now light three lamps - one near where you entered from the elevator, one near where the BEETLE was found, and one in an alcove in the north wall of the central room.
The door in the eastern room will now open. Outside, push the lever on the catwalk to open the gate to another elevator back near where you found the KEYS. Push the button to raise the elevator. Climb out and explore the small network of passages for several pickups. Notice a higher passage leading off to the west. Before going there, you'll need to shoot the brass sphere located in a dark corner of one of the passages. This opens and underwater door in a nearby fountain.
Now follow the higher passage to the fountain and shoot the SAS guard waiting there. Jump in the water and swim through the tunnel. Climb out into a small room with some sandstone blocks. Lara will have to move the blocks in a way to clear the NE corner, where a lever is located. Pull the lever and return to the area with the series of passageways. In the SW corner, a block has been raised to access an alcove above. Climb up and take the DJOSER PILLAR, as the iron door below swings open.
Exit via the iron door and to find yourself outside. Cross to the opening opposite and use the TOWER KEYS in the lock , which opens a nearby gate and retracts the spikes at the begining of the level. Head through the gate and turn left immediately as an automatic gun starts firing. Head directly east along the wall to the end. Then head south along the next wall. At the end, make a run into the room where you began the level. Crawl through the small opening and drop on the other side. Blast a skeleton lurking there. Around the corner, target the automatic gun through the opening in the wall and destroy it.
Head back to the other courtyard and pull a lever on the wall near where the automatic gun stood. Look through the opening in the wall to see a new open near the pillar. You can also destroy the other gun now from the nearby SW corner. Once more, crawl back through to the outer courtyard and find the open well near the pillar. Get the DJOSER PILLAR at the bottom and return to the inner courtyard. Now go down in to the tunnel where you first drove the motorbike. At the dead end, pull the block on the left out until Lara can get through the opening. On the other side, jump and pull the switch on the wall to reveal the passage that brings you to the secret #3 :
Return to the courtyard and back through the gate to the tower rooftop. Safety drop down through the small opening near the iron grille. In the room below, find the receptacle for the first DJOSER PILLAR on the north wall. Placing the PILLAR opens the nearby iron door, leading back to the roof The third and final BLACK BEETLE is found In the SW corner of the room. Now, head down the ramp and retrieve your Lara's motorbike. On the way, step back in to the shaft of the first elevator to find a crawlspace leading to Secret #3.
Now, ride the motorbike all the way to the rooftop. Turn right and head though the next opening. Ride down and over the ramp, jumping and clearing a pool, to land on the other side. Place the second DJOSER PILLAR in the receptacle to open the exit door. Before leaving the level, ride the motorbike back to the rooftop using the side tunnel. Outside, drop down through the small hole again to the room below. A sphinx door on the south wall is now open and inside waits Secret #4. To finish the level, ride the motorbike back over the jump and exit through the open iron door.