Underholm is the common translation of the Dwarvish word for "hollow delving" aka Hollowbold, found in the subterraneous north-central part of the Giantwalk mountain range, near Mount Dol where the Dwarf-road of Bele crossed the river Knee Deep. It was founded to guard the naturel pass through the Giantwalk, and grew to become the ancestral home of the Dwarven clans. The great Dwarven smiths Zamil Girak and Chartel were responsible for the forging of the great Adamintine Gates of the Underholm
The city was built sometime during the Years of the Trees, known as the first age by Imperial scholars, when The Dwarven King is first recorded to have appeared in Mundis.
Underholm traded with throughout The Dragon Empire of the first age, and extensivly with The Elf Queen. The Dwarves were employed for delvings and crafts, most famously the crown of the The Emperor. Eolenta the father of Drow often went there, as did his son Maeglini Talvaeth.
At the end of the First Age, Underholm was ruined in the Pogrom of the Underhome, where under the command of Gruumsh, The Orc Lord, the hordes of the orcs and giants sacked the hallowed halls and razed Axis.