Dwarves
Dwarves are one of the most enigmatic mysteries of the Known Worlds. Ruins and other evidence of their civilization are found everywhere, including in a variety of impossible places. Much fine artwork, including detailed depictions survive. They are also discussed in The Book of Lore, and described as having fought beside humans during the Mythical Age on both sides of the conflict. However, how much of the surviving information is accurate remains a question of scholarly debate.
While artwork depicting the dwarves is well known, no remains have ever been found, and their writing remains impossible to translate, despite large volumes of it having been found. The complete lack of remains and dirth of individual artifacts has made discovering anything about their culture or biology a near impossibility.
Holdings
The most common type of ruin associated with dwarves is called a "holding". These are often elaborate underground structures that served as both home and work spaces, and in every intact example were also connected to extensive mines.
What makes the holdings especially enigmatic is that they have been found in places that never could have supported life. Among the strangest discoveries related to the dwarves is the existence of a holding on an icy moon orbiting a gas giant. The holding is located beneath two hundred miles of ice, where it sits within a large rock formation that was mined. While the facility is exposed to vacuum, a single door fitted in the right spot would allow the entire place to be pressurized.