The Grenroa Clan is one of the Dwarven mountain clans. They are responsible for the massive underground network of tunnels and secret passages that connect all of the dwarven communities and mines, built over the course of three thousand years.
Among their works are the tunnels that connect the city of Zul Logoth to above-ground settlements to the east and west of the Dragonspine Mountains, through which the Grevnek Clan later built a system of mining carts to facilitate trade across the mountains, making Zul Logoth one of the essential trading centers of Elanthia.
Grenroa tunnelers often work together with Toktrog Clan trailblazers to connect new settlements to the great dwarven underground.
Chiostolis, the Labyrinth
Chiostolis is the great labyrinthine city of the Grenroa Clan, lying beneath the northern reaches of the Dragonspine Mountains. With stone walls nearly six elves high in some places and over 500 mapped alcoves and rooms, this tremendous maze daunted even the heartiest of navigators, leaving the Grenroa dwarves to live in relative peace, and able to focus on the task of maintaining the vast miles of tunnels deep within the Dragonspine.
- A History of Dwarves, Chapter 6.