Doga-Delloth is one of the Vaults of Orv, the lowest level of the Darklands. It is located on the shore of the Sightless Sea, with the xoarian1 home of Ilvarandin to the north, and the Black Desert to the east.2 Doga-Delloth is the heart of the vile urdefhan empire,3 with other settlements in the Midnight Mountains, on islands in the Sightless Sea, and in Ilvarandin.4
Urdefhans have built a network of roads across the Vault, linking together their cities and fortresses. Urdefhan settlements are most common on the coast of the Sightless Sea or near the primary tunnels leading in and out of the Vault. In all, urdefhans have eight major cities, with the northernmost city of Niovengia on the Sightless Sea chief among them. While urdefhan settlements exist throughout the Vault and most of it can be considered "civilized", there are also many wilder and less densley settled sections.4
For additional as-yet unincorporated sources about this subject, see the Meta page.