Zyrreth

Zyrreth is an isolated city that is almost central within The passing lands.
The city is below the sands of the passing lands. It is a city made mostly with a somewhat different looking sandstone.
Underneath the sunlight it looks like some of the walls and ceilings are either reflective of the sunlight or make light themselves. However when the sun goes down the entire town is covered with a dim dark cyan colour. Making the entire atmosphere of the town from a bussy city go to an almost mysterious town where you aren't sure if you are still in the material plane or entered a different dimension.
The way this city keeps itself alive is mostly through Sener's heart. The magical casters perform a ritual to purify the water and make it keep the properties it currently has.
The city has dinosaurs not as pets however as partners. Each of them usually only bind with one person and that is the one they grew up with though there are some that bond far more easily to others and others that refuse to bond at all. If the relationship between the animal and the humanoid is strong enough and both of them want it. (The caster of it needs to know speak with animals to confirm the dinosaurs willingness) They go through a ritual to bond with each other. With that bond they can sense the general direction the other whenever they want to. They also gain the ability to know whenever the other is hurt. And as a final benefit they can help each other grow both in battle and as a person (think of something cool mechanically that that would imply) (maybe this entire city or a lot of it is comprised of of firbolgs or more animal loving humans)

This city however hasn't been seen in a long time and is mostly thought of as story or a myth especially because of the dinosaurs that are said to be within the cities proper however nobody has ever seen such a creature.