Take Yorda's hand and head across the old bridge. Somewhere along the way, a section of the bridge behind Ico and Yorda will collapse, preventing them from going back. On the other hand, there's no need to. As long as Ico has Yorda by the hand, she will not fall along with the collapsing section. Continue on to the next set of Idol Doors and Yorda will again cause them to open. A pressure switch will be seen to arise from the floor and the door behind the Idol Doors will close. Have them stand on the pressure switch to open the door and walk through into the Proto.

There are a fair number of pots lying about, which can be thrown at enemies, but aren't nearly as effective as your weapon, though they can bounce around and take out one or more of the Spider Wraiths. While the Spider Wraiths can not pick up Yorda and carry her, if several of them clump together, they can form into a larger humanoid spirit, which can. A spirit portal will open as they walk down the wide staircase. Destroy the spirits to extinguish the portal (you'll see some smoke emanating from it when this happens). There's a pressure switch in front of a door on the opposite side of the room from the entrance. It's a dead end and can be ignored. Note the block down in the aqueduct to the left of the ramp as you entered. Press the 'Circle' button and move the left analog mini-joystick in the direction you wish to move the block. Any of the four major directions will do. A pressure switch will arise and trigger the appearance of a circular staircase on the other side of the room. Head up the staircase and through another door. Continue along the balcony outside to another door, which leads into the Main Hall.

You'll notice that your progress is quickly blocked when you approach the next door in your way, which can not be opened from this side. Have Ico climb up on the railing and jump off down to the floor below. Move Ico in the only direction he can go up the two small sets of stairs. There's a lever off to the right. Have Ico pull the lever to open the door and call Yorda. After she's joined Ico, head back down the two sets of stairs into the area, where Ico jumped off the railing. There's a chain hanging near the other side, and a box up on the ledge. When Ico climbs up the chain and jumps onto the floor of the ledge near it, four shadow wraiths will appear. These guys are stronger than the last batch and can knock Ico over and temporarily stun him. Have Ico push the block straight over the edge and jump down to engage the enemy. They can be dealt with fairly easily by flailing away at them without getting too close to them. Note that Ico can hold Yorda's hand while fighting. If she's carried into the black pool, hurry over and press 'R1' to pull her out, then immediately move away and continue whacking the wraiths. Once they're dealt with, have Ico climb the chain and jump onto the ledge again. Stand above the right half (facing it from the ledge) of the block and press and hold 'R1' to call Yorda. You'll know you've done this correctly if Ico leans over the ledge and extends his hand and Yorda climbs onto the block and jumps to grab his hand so she can be pulled up to the ledge. If this does not happen, have Ico move just a little way along the ledge closer to being in line with the box and try again. Once successfully accomplished, they can head through the door and on to an outside pathway.

Climb up the stairs onto the periphery wall, where you'll see more shadowy creatures preparing to attack. Two of them can fly, which marks your first encounter with the Crow Ghouls. A Crow Sentry also appears. Move in from the stairs Ico and Yorda came up on or Ico may be knocked off the ledge and you'll get to start this section all over again. The flying Crow Ghouls can pick Yorda up and fly off with her to the black portal pool. You should attempt to prevent this, because if you have to run over to the black pool to try to pull her out, you'll almost certainly be knocked off the ledge and be unable to get back up there in time to save her. The best strategy is to keep an eye on Yorda at all times during the battle. As soon as any one of the enemies goes for Yorda, attack it, without worrying too much about the other two. Switch to the next one as soon as it heads for Yorda. You must destroy all of them to advance. Have them walk past the small lookout tower over to the other end of the area. Have them enter the alcove on the left and sit on the stone couch and save your game.