Sol Sanctum is a sacred place for the inhabitants of Vale, and your first dungeon. Although Sol Sanctum contains some monsters, there is nothing that is particularly dangerous or taxing. When you enter Sol Sanctum, Isaac has the Cure, Move and Retreat psynergies, Garet has Move and Flare, and Jenna only has Flare. You will almost certainly gain a level in Sol Sanctum, and Isaac learns Quake at level 2, meaning that all three characters have an area-attack Psynergy. You will not have many Psynergy Points (PP) this early, so use Psynergy only when necessary.
Once you’ve entered Sol Sanctum, go immediately north.
This room is home to your first jumping puzzle. Go to the far right and jump forwards. Jump forwards twice more, then left twice, then down twice, then left once, then up three times (if that confuses you, use the map to the right), then exit to the north. Follow this path until you reach the next door.
The next room is another jumping puzzle. First, take the middle path and open the treasure chest you find there. It contains a Small Jewel. These jewels are the missing eyes for the minotaur faces you find, and are used to open previously hidden paths. Take the right hand path, and press A on the minotaur head. Go to items, and then select the Small Jewel you found and use it. This opens the path on the left. Go back and take the left hand path, and enter the door to the next area.
Kraden says that this room is the furthest he has ever been into Sol Sanctum. He says that there is a hidden passage that you need to find. Go right, and look at the statue with the odd dotted line on the ground surrounding it. This is used to show movable objects in Golden Sun. Walk up to the statue and push it to the right, then enter the doorway behind it. Then go straight up the stairs.
From here, head right, and go straight up until you reach a crossroads.
First, go left, follow the path around, and get the Small Jewel from the treasure chest. Return to the crossroads, and take the middle path. Follow it around until you reach another doorway.
Now, you are in a room full of statues that you cannot reach through normal means. Go to the far left, and step onto the block. Then cast Move on the statue, and move it to the left. Jump forwards, and put the Small Jewel back into the minotaur head. This opens up a new passage. Now go to the far right, and move that statue out of the way, revealing the newly opened passage. Head forwards through the new doorway.
Move forwards to the T junction, and take the left hand path. Open the treasure chest you find to gain a herb, then go to the right, then forwards to find the heart of Sol Sanctum. After the cut scene, go right to find another room, and trigger another speech from Kraden. Go further down the passage, and up the stairs.
Before you go north, go south and through the doorway. In this room, there is a Psynergy Stone. Make sure you have your party at full health before you use it, as it restores all of your PP. If your party is not at full health, use Cure to heal them first.
Going north reveals a room with four statues that are all one square out of place. Do not move them yet. Instead, go to the left, until you find five statues. Move the left and right statues back onto their pedestals. This makes them shine a light on a spot on the ground, and create a hole. Use Move to move the remaining statue into the hole.
Now, go right again. Move each of the statues onto their pedestals (you will be interrupted after the first one by a cut scene). After completing this, backtrack to the room that previously had a Luna (crescent moon) symbol on the floor. After the cut scene, go left, and press A on the point where the line of light hits the wall. This opens a portal.
Your party appears in the Elemental Star Room. Kraden will explain about the elemental stars, and ask you to fetch them for him, using four Mythril Bags.
Go to the top right part of the platform you are on, and jump upwards. When you reach the first branch, go right. Follow this set of jumps around and press A on the glowing statue to collect the Venus Star. Backtrack to the branch you went right on originally, and this time, go upwards, then right. Collect the Mercury Star. Backtrack to the main platform, and then go downwards. Then collect the Jupiter Star.
This triggers another cut scene. Saturos and Menardi (the mysterious man and woman) and been revealed to everyone in the room. They reveal another mysterious stranger is Felix – who was originally thought to have died when the Mt. Aleph boulder hit. Garet gives them the Elemental Stars you have collected so far, and they demand that you collect the Mars Star for them as well. Jump back to the main platform, then go up again. Go past the Mercury Star, and follow the path around to find the Mars Star. Collect it to trigger another cut scene.
The others flee the room through the portal, taking Jenna and Kraden with them. A floating rock with an eye (The Wise One) tells you that the Stars are moving away, and the Djinn have returned. He then teleports you back to the Luna room. Use Isaac to cast Retreat, and head south to leave Sol Sanctum.
After leaving Sol Sanctum, you will find yourself in the Sol Entrance. Leave this area to the south to return to Vale.