The Dragon City of Warfang is located somewhere in relative vicinity of the valley of Avalar. It is a large city made mostly out of stone, with architecture utilizing mechanical systems, mostly using statues as triggering mechanisms, similar to the Dragon Temple.
Warfang is a massive city built by the moles, using mostly stone in it's construction. The stone seems mostly golden in color, however, it might be because of the red light from the volcano. Throughout the city, a wide variety of crystals clusters of all colors was located. The wall circling the city is built out of the same type of stone as the rest of the city, but seems more capable of withstanding attacks, likely due to it being built out of massive stone. On top of the wall, a massive canon was located.
The city made use of multiple mechanical constructs, using statues of various dragons as activation mechanisms. One example was one of the watering systems, who sent water through the head of a two statues that worked one at a time. The gate of the city was built using similar constructs, but utilized lava in the locking mechanism. The lock could not be activated instantly, but required the gate to be shut for a short amount of time. The gate seemed strong, as it could withstand most attacks, only being forced open when Malefor's forces used a battering ram.
Between Warfang and the Dam there was a network of underground tunnels known as the Underground City. This may imply that the city once reached much farther than it does today, but have been destroyed and rebuilt one or multiple times.
Before the LoS-series
The Legend of Spyro: Dawn of the Dragon
Warfang was one of the first places to be besieged by Malefor's forces. With the help of the moles, the dragons managed to fend of the dark master's armies for possibly two or three years. When Malefor summoned the Destroyer, the Guardians, along with multiple dragons and moles, escorted Spyro, Cynder and Sparx through the underground ruins of Warfang, hoping that by traveling underground, they'd not let Malefor know that the city was left practically undefended. When the Destroyer reached it's goal, Sparx, along with Cyril, Terrador and Volteer, as well as the rest of the forces that went with them, were sent back to Warfang to lead the citizens to the underground ruins, where they hoped they'd be safe from the destruction of the world.
At the end of Dawn of the Dragon, the three remaining Guardians are seen with Warfang being reconstructed behind them.