The City formed the core of the D'ni empire, and most of the D'ni structures and population was centered here. The main Cavern which houses the D'ni city holds an underground lake which contains an unidentified species of luminescent algae. These algae gave off enough light to light up the entire Cavern, in a 30-hour cycle which formed the natural day and night for the D'ni. Through unknown means of poisoning the algae nearly all died off, and still have not fully recovered. The result is that level of light these algae give off was diminished. It has, however, been revealed in Uru: The Path of the Shell that with the proper food (a form of highly processed grain) the level of light these algae give off can be dramatically increased temporarily.
The lake holds multiple islands, of which the largest is Ae'gura. Other large islands were held by the richest families, such as the island of K'veer. On the lake "shores", hugging the cavern walls, the City Proper was built.
Grain Silo ([Uran]]) Edit
The city held several silos to store the food brought in from the various Ages. One of them, a grain silo, can be reached through the granary age of Er'cana. It is unknown where the silo precisely is located, but the locational markers on the KI suggest it is inside the main Cavern, but far away from Ae'gura, in one of the industrial districts which cannot be visited. This particular silo served to store food for the luminescent algae in the main Cavern, not to feed the people of D'ni. During the time of the D'ni civilization, this Silo was known as Uran, and later Ashem'en.
The Great Shaft was a joint project of the Guilds of Surveyors, Miners, Stonemasons, and Cartographers, which attempted to build a tunnel and shaft to the Surface. Although the project was abandoned just before completion, it still allowed for a way from D'ni to the surface. The "end" of the Shaft is located near the Cleft. These tunnels are coated in nara, a form of highly processed material which is nearly indestructible, and gives off light. The other caverns are now mostly dark, but most of them were lit through unknown means in the past.
Neighbourhoods of the D'ni city are the city areas which hug the edges of the main cavern. They are based on a few basic forms, with only small differences between them. The neighbourhoods are inaccessible except through the Nexus, which perhaps explains why they are mostly undamaged.
The Watcher's Sanctuary, also known as the Great Tree Pub, is a completely enclosed area located in the J'taeri District of Ae'gura. This location, while also based in the Cavern, was unreachable without Linking Books.