This page explains how to complete the level 86 Endwalker quest "Return to the Crystarium".
This quest is available if you have completed the quest At World's End, and have reached level 86.
Starting the Quest
Talk to G'raha Tia in Radz-at-Han to begin the quest.
Speak with Lyna
Teleport to Fort Jobb in Lakeland and go southwest to where the orange arrow is pointing in the minimap. Talk to Lyna to proceed. There will be a cutscene.
Wait for Lyna in Front of the Cabinet of Curiosity
Go southeast to enter the Crystarium. Go east to the Aetheryte Plaza and use the Aetheryte to go to the Cabinet of Curiosity. Go to the quest icon on the map and check on the sparkling Destination. There will be an unskippable cutscene. Say Yes to proceed.
Speak with Ryne
Talk to Ryne to complete the quest. There will be a cutscene.
Next Main Scenario Quest
After you complete the quest, talk to Ryne to accept the next quest: Hope Upon a Flower.