Borrorill is a large hill on the outskirts of Trebon, near the Mauthen farm. It is said to be named in reference to local superstition that it is a barrow or burial site.
Before being murdered Mauthen digs up flat grey stones from the hill and uses them to build a home. Other residents think this is a bad omen, as they assume the stones are gravestones. This is also where Mauthen digs up the pottery showing images of the Chandrian and an Amyr. 
- The Name of the Wind, Chapter 72, "Borrorill"