Shield of Hades
The room reached next should have a bridge and an ambush of enemies including Medusas. Kill them all for the orbs and then head through the passage to the other side of the room. Here you should find a crate and another narrow hallway leading into another room. Grab the crate and bring it into the new room, where you'll be attacked once again by a group of Undead Archers and Medusas. After killing them all, go to the first room with the bridge and jump up to the stairs that lead to a boarded walkway. Balance across to the lever, pull it with , and then slide down the chain that's just been lowered. Now you should be in a place with a horizontal rope leading off of an isolated piece of land. Jump onto the rope and climb across (while fighting off the enemies along the way), go up the stairs, and retrieve the Shield of Hades.
Shield of Zeus
Once you take it, a barrier will come up and the wall will start to move. You have to defeat all of the enemies that spawn before you can get crushed by the wall. The barrier will disappear once you've killed them all and the path will be open. Climb back up the chain and go back to the room where you left the crate. Every time you push the crate onto the elevated spot in the ground (the switch), the wall at the front of the room will turn around. However, your time is very limited - so much that it would be impossible to run all the way from the switch to the wall in the given amount of time. You have to go up to the wall with the box and then, so you're facing the switch and the box is in front of you, kick the box hard enough so that it reaches the switch and the wall turns. In the new room, climb up the ladder, jump across the gap, and take the Shield of Zeus.
Handle of Atlas
Jump down and put the two shields into the door with the soldiers on it. The door will open, revealing a new path. Go down the stairs and keep following the path until you reach a room with many saws that travel along the floor. Wait until the saws stop to move, and repeat until you reach the passage to the right of the room. Break the wall and get down the conveyor belt while avoiding the traps (by moving as quickly as possible at the right time) and you'll eventually reach a bridge. Before passing through it, jump to the platform in the background for a Phoenix Feather. Climb the ladder and continue onto the wall. Keep jumping right until you reach a dead end, then go up. When you reach the top, go left until you reach the platform with the lever. Go through the passage on the platform and then kill all of the Undead Legionnaires and the Sirens in this room before the floor breaks through. Try to take advantage of Medusa's Gaze in this situation.
When you're done with the enemies, take the Handle of Atlas at the end of the room and then leave the way you came. Pull the lever and slide down the chain. Eventually, you'll reach the room with the saws again. This time, you'll have to get the bars open. Do this by pulling the two levers at either side of the room as quickly as possible. This can take a while, but it's definitely possible in a few tries. The next room has a large gap in the floor. Get across by shimmying along the wall and then lifting up the wall with the handle. Attach the Handle of Atlas to the crank and then turn it to bring up the statue of Atlas. Open the chest by the statue for a Muse Key. Then go to the other side of the room and climb the stairs. Now you should have a higher view of the statue of Atlas. Pull the lever and a new path will open. Go up to the coffin, pull off the top, and take the head. Now take the path back to the Rings of Pandora to get started on your quest to the Challenge of Poseidon.