Deep Roads

The Deep Roads are a grand network of enormous underground tunnels that once belonged to the dwarven empire, spanning the length and breadth of Thedas. These subterranean highways were works of unparalleled artisan achievement, with centuries of planning and engineering demonstrated in the geometry of their walls. Statues of the Paragons watched over passing travelers, and channels carried a flow of magma that kept the Deep Roads lit and warm.

During the First Blight, the dwarves were forced to close the entrances to the Deep Roads, abandoning them to the darkspawn. The entrances still exist, but are all sealed by octagonal steel doors decorated with geometric patterns that may form words or patterns.

The entrance at the dwarven city of Orzammar is also sealed, though the gate is opened on occasion for one of the following reasons:
 * People who have been granted access or authorized expeditions.
 * Regular operations conducted by Orzammar's army.
 * Grey Wardens who head to their Calling.
 * New members of the Legion of the Dead who venture into the Deep Roads, where they spend their last days fighting the darkspawn in hopes of redemption.

Background
The Deep Roads are a grand network of tunnels that once linked the thaigs, the caverns where settlements were built in honor of the Paragons - dwarves that achieved legendary status among their people. These subterranean highways were works of unparalleled artisan achievement, with centuries of planning and engineering demonstrated in the geometry of their walls. Statues of the Paragons watched over passing travelers, and channels carried a flow of magma that kept the Deep Roads lit and warm. At the height of the dwarven kingdom, the Deep Roads were busy with constant travelers and merchants, not only from the thaigs, but from the surface. If a citizen of the Tevinter Imperium at its height were to see the Deep Roads today, they would be shocked at the silence and decay that now reigns within.

This once-proud creation is now the source of much lament for what the dwarves have lost. Today, only two thaigs remain inhabited: Kal-Sharok deep beneath the Hunterhorn Mountains and Orzammar beneath the Frostback Mountains.

How much of the network is still open is unknown, as is how much of the Deep Roads the darkspawn have corrupted. It has been centuries since the darkspawn invaded the surface, but the fact that it takes the Darkspawn some time to break through to the surface (and the fact that they have to break through instead of just emerging) suggests that most of the official entrances are well-sealed. Entering the Deep Roads brings great risks. There are many legends of travelers going missing in the hills near these entrances, most coming from Ferelden.

Despite the danger, many still enter the Deep Roads. Several attempts have been made by the Dwarves to retake lost thaigs, most notably the Aeducan Thaig near Orzammar, but all have failed. Grey Wardens who experience the Calling travel to the Deep Roads to fight their final battle against the darkspawn, as do dwarves who join the Legion of the Dead.

Travel
Travel within the Deep Roads is difficult. Many of the caverns leading down have been partially filled in with rock and earth, either on purpose to keep what is down there from getting to the surface, or through neglect and the passage of time. Many smaller tunnels intersect with the Roads themselves, making navigation even more difficult, but sometimes allowing blockages or other obstacles to be avoided. There is air available even in the deepest portions, as the dwarven craftsmen that built the roads created an intricate duct system to supply it. Natural light however does not reach the Roads so channels of magma, slow-burning torches that have been burning for centuries, and other forms of technological illumination are used to provide light. The intersections have dwarven runes carved into walls, which may indicate directions.

Along the network of passages are abandoned way-stations and forts, as well as the empty ruins of thaigs lost to the darkspawn.

In the more ancient parts of the Deep Roads, the walls and floor are covered with a substance of oil and filth - a visible indication of the taint, spread even to the rock itself, by the darkspawn that exist there.

The Primeval Thaig
There is no mention of the Primeval Thaig in the records and memories of the Shapers. In the thaig itself, things are very different from the rest of the Deep Roads. There are neither statues of the Paragons nor signs of darkspawn corruption. Even more bizarrely, there exist magically-created objects and temples to some deity, which is unusual because dwarves do not have a God-like figure. Structures incorporate lyrium, which today would be considered a very unsafe practice.

Bestiary
After the dwarves lost control of the Deep Roads, some of the wildlife from the underground caverns and tunnels now lives into the Deep Roads and lost thaigs. However it is not numerous due to the presence of darkspawn and because of the darkspawn taint which affects their fertility as well as turning some of them into ghouls. These are the known animal species:
 * Bronto
 * Deepstalker
 * Glowing slime
 * Nug
 * Rat
 * Spider

Enemies

 * Corrupted Spiders: A warning sign is the distinct chittering sound and numerous webs.
 * Deepstalker: Deep Stalkers are found throughout the Deep Roads. They feed on anything they can get their fangs on. They also have a tendency to ambush the party by having one Deep Stalker lead them into a trap - this can be avoided by killing the Deep Stalker before it can reach the ambush point.
 * Genlocks: A short and numerous type of darkspawn.
 * Hurlocks: Taller than the genlocks, they are acting as the heavy infantry of the darkspawn.
 * Shrieks: The only known warning sign for an encounter with the deadly shriek is a strange deep humming or moaning sound performed in an almost chanting fashion.
 * Ogres: Giant and powerful darkspawn as well as very rare.

Trivia

 * Despite the fact that the Deep Roads are constantly teeming with darkspawn (especially when compared to the surface), they are safer during a Blight with the exception of the First Blight.
 * The party never experiences random encounters whilst traveling from an underground location to another.
 * On the map of the Deep Roads, there are paths that lead to four symbols (e.g. the dual axes toward the bottom left, and the golem at the middle top). There are no quests that let you explore these areas.
 * The map only shows a tiny portion of the Deep Roads. As mentioned in the epilogue of Origins and during Awakening, the network extends under a large portion of Thedas. It is confirmed they go at least as far as the Free Marches and the Hunterhorn Mountains.