You’ll need three Yellow Fragments to restore this pillar. You can find them in Alltrades Abbey and Al-Balad. Doing so will let you travel to Gröndal and continue the main story.
Warning: This guide contains some minor spoilers for Dragon Quest VII.
Finding the first fragment
You’ll find the first piece after completing the Alltrades Abbey main quest.
After a cutscene and spawning on the top floor of the Abbey (where you can change your vocations now!) exit the place and head back to Pilgrim’s Perdition.
Most of the town is empty now. Go to the Bank building to find out no one is working there anymore, so you can pick up the Yellow Fragment behind the desk. You can also open the chest to get a Seed of Strength.
Finding the second fragment.
Similarly to the previous fragment, you can find this one after completing the Al-Balad main quest.
After talking to everyone in town and saving the place, go inside the small hut on the east side of the town, which was previously guarded by an old man. You can now open the rightmost room to get the next Yellow Fragment. There’s also another chest in there where you can find a Leather Whip.
Finding the third fragment
After getting the second fragment, head back to Temple Palace. You’ll find Digby hanging around. Talk to him and he’ll tell you he doesn’t want to go back to the present, and he’ll give you a Care Package.
Return to the present now, and sail or Zoom to the Dig Site, on the same island where the Roamers Encampment used to be in the past. New people are working there, and they’ll charge you a bit more to enter (10g instead of 5).
Enter the tent and exit through the west, and give the Care Package to the man guarding the excavation site, so he lets you pass.
Follow the main path, skip the first staircase down you see and take the next one that goes down. Keep following that path and you’ll find the third Yellow Fragment lying on the floor.
You have all the fragments you need! Zoom back to the Shrine of Mysteries and place them in the lower left Yellow Pillar. Doing this will teleport you to Gröndal, where you can continue your main story.
Note: fights can start getting more difficult from now on, so this is a good time to grind some levels and learn a good vocation for each character before heading to Gröndal.