The Ruins

The Ruins are the first main location in the Underground.

Main Story
Frisk falls down and, after being attacked by Peacemaker, is rescued by Hope. She leads them through part of the Ruins, eventually leaving them to prepare "a surprise." After walking through the Ruins and battling various dragons, they meet Hope near her home, and she reveals that she was planning to bake a pie for them.

History
The Ruins were once Home, the first place where animi lived after their exile. However, as dragons explored the rest of the Underground, fewer and fewer lived in the Ruins, and the few remaining moved into the mostly abandoned castle.