Canterlot Ruins

Before the War
Canterlot is the holy place where princess Luna and princess Celestia once lived. Before the war, Luna was placed inside a facility along with chosen ponies to repopulate the future while Celestia deals with the war. However, princess Celestia promised that she would be with her little sister so she got herself scanned and copied her current memories, behaviour into a microchip that was later added into the sentient robot body of Celestia that looks exactly like her and doesn't make any metallic noise due to the tissues that were elastic rubber that prevents metals clashing. The facility is located at the very bottom of the mines in Canterlot, deep within the mountain where the castle rests. Housing Luna and the others in the facility and the plants, seeds, other resources to be replanted for the future. Its the last remaining hope to remake Equestria if everything goes wrong, at least they had a backup.

After the war. Canterlot remains with a shield that tried to protect it however as the shield wilts from the balefire bombs the Legion kept bombarding them, it has failed and become a devastated ruin. Celestia died in the aftermath.