As creations of Aulë, they were attracted to the substances of Arda. They mined and worked precious metals throughout the mountains of Middle-earth. They were unrivalled in smithing, crafting, metalworking, and masonry, even among the Elves. The Dwarf-smith Telchar was the greatest in renown. They built immense halls under mountains where they built their cities. They built many famed halls including the Menegroth, Khazad-dûm, and Erebor. Among the many treasures they forged were the named weapons Narsil, the sword of Elendil, the Dragon-helm of Dor-lómin and the necklace Nauglamír, the most prized treasure in Nargothrond and the most famed Dwarven work of the Elder Days.