Part 25: Chronopolis - Chrono Cross Guide - IGN

Once everything is done, go to the Dead Sea Ruins (Home), and interact with one of the three glowing points in the water.

Part 24: Characters & Techs 2 - Chrono Cross Guide - IGN

Part 25: Chronopolis - Chrono Cross Guide - IGN

Part 24: Characters & Techs 2 - Chrono Cross Guide - IGN

Part 20: Viper Manor Revisited - Chrono Cross Guide - IGN

Part 23: The Dragon Tear - Chrono Cross Guide - IGN

Part 25: Chronopolis - Chrono Cross Guide - IGN

Part 23: The Dragon Tear - Chrono Cross Guide - IGN

Part 01: Arni Village (Home) - Chrono Cross Guide - IGN

Part 10: S.S. Invincible - Chrono Cross Guide - IGN

Part 25: Chronopolis - Chrono Cross Guide - IGN