Darkmount is a fortress on Cybertron, the capital of Decepticon-controlled Polyhex. For a period of time during the Great War it was the seat of power for Lord Straxus, who fed dissenters to the smelting pool, a cauldron of magma which sat menacingly in Darkmount's shadow.  The smelting pool empties through ducts into a canyon which Darkmount overlooks. 
Marvel Comics continuity
Wishing to prove himself to his Autobot comrades, Scrounge infiltrated Darkmount. He was able to intercept a transmission from Earth, but he was caught. Blaster tried to rescue him, but Scrounge met his end in the smelting pool.
Meanwhile, the Space Bridge was being constructed under Straxus's supervision in a massive chamber located nearby.
To keep the Decepticons from using the new Space Bridge, Blaster's group of Autobot resistance, led by Perceptor, orchestrated a siege on Darkmount. The digging efforts of Borebit and Corkscrew loosened Darkmount's foundation, causing it to crumble, while Blaster defeated Lord Straxus on the Space Bridge.
The head of Lord Straxus survived, but with the destruction of Darkmount, he relocated to another stronghold in Polyhex.
Universe: Featuring the Wreckers
- Mercy is not dispensed there.
- Death is the only thing dispensed there, fool.