Zin-Azshari
Zin-Azshari was over 10,000 years ago the heart of the Kaldorei Empire. The highborne lived here and served their Queen Azshara in the palace – but the entire city around it was a huge metropolis inhabited by hundreds of thousands.
In the heart of Zin-Azshari was not only Queen Azshara’s palace, but also the Well of Eternity – a large lake full of magical power that the highborne tapped into and explored. This very research led the Burning Legion to take notice of Azeroth.
Azshara attempted to bring Sargeras through the portal to Azeroth to help her “liberate the world from all that is unworthy” and then to have him as her consort by her side.
The plan, however, was thwarted by some heroes (including a legendary time-traveling Orc). When the portal collapses, the magical energy is so devastating that it not only tears apart the city of Zin-Azshari but also the entire continent. The city is destroyed and flooded by gigantic waves, killing almost all its inhabitants.
Azshara survives the incident and then makes a pact with the Old God N’Zoth, who transforms her and some of her surviving followers into Naga.
Zin-Azshari was so large that parts of its ruins can be found all over the world. No wonder, as the world was torn apart right in the middle of Zin-Azshari, leaving several parts of the city scattered in different directions.
The largest ruins can be found in Azshara and Naz’jatar, but small remnants can also be found in places like Desolace.