Suramar

Suramar is the city Malfurion, Tyrande, and Illidan grew up in.

A zone coming in the expansion Legion, Suramar is an ancient home of the Kaldorei.

Exploration: Explore Suramar
Quests: Nightfallen But Not Forgotten

Suramar has a long, rich Night Elf history.
Historically, you could have found the Temple of Elune/Suramar's "Temple of the Moon" (a temple... for the followers of Elune), the Boughs of Azshara (sacred trees), Izal-Shurah (a great library), Arauk Nashal, "great arcane academies", and many more elven sites.

The current day zone Suramar is home to a raid [zone=8025] (the Palace, located within what remains of the city), dungeons [zone=7855] (located underneath the city) and [zone=8079] (the Noble District), and a Scenario, [zone=7767] (set to be the scenario for obtaining the Demon Hunter Havoc (dps) spec's Artifact weapons, [itemset=1264]).

The Pillars of Creation have historically been tied to this zone, having previously been used to heal the land.
At that place of healing is where you would have afterwards found the Temple of Elune (where Tyrande once studied to become a priest of Elune), a more desolate area now called the Tomb of Sargeras (where Aegwynn entombed the remains of the Avatar of Sargeras).

Where now lies the Tomb of Sargeras, Tyrande once studied to become a priest of Elune, in the Temple of Elune, which the elves built upon the place in the earth they had healed using the Pillars of Creation.

Suramar Palace itself is the Palace of the Nightborne, home to the Nightwell, a source of power for the Nightborne.
These Nightborne were once the Highborne, as Suramar was originally a Kaldorei city.
Long ago, to protect themselves from the Great Sundering, Grand Magistrix Elisunde, and the Highborne who remained in Suramar City's Palace, created a magical shield, protecting the Palace, but according to lore, most of Suramar disappeared into the depths, as with Azshara.
Many years later, The Broken Shore ( a small portion of the Broken Isles, near current day Suramar City, was raised from the ocean by MU Gul'dan. It is currently unclear how much of Suramar, and the the Broken Isles in general, was submerged, and if much was submerged, as lore has previously told us, how the rest of it (every submerged part but the Broken Isles) was raised from the ocean's depths. Hopefully this will be clarified by Blizzard soon, or during all the zones' questing.

The Highborne within the city were afraid of what wasteland might lay outside, so the shield remained active, and, consquently, these Highborne gradually became dependent upon the Nightwell and evolved into the Nightborne.

These elves have since lowered their shield, and allied with the Burning Shadow (also know as the Burning Legion).

There is a US Server named after this zone, and you can find its wow Forum here.

Slight correction/addition from the beautifully written piece by Nynaeve Sedai. The nightborne are not known to be addicted to the nightwell, rather they have become dependent on it as one is dependent on food.

This came about because some time into their seclusion, these night elves of the city exhausted their food supply and started to starve, so they ingeniously adapted the nightwell waters to be ingested and thus were sustained directly by it. They require the actual substance called arcwine which comes from the nightwell. It is the absence of this that will cause them to starve and eventually turn into Withered where others would just die.

So you see, it is no more addiction than requiring food is considered addiction, though like food it is possible some may become addicted to it, however the impression I get is that they are a very disciplined and accomplished society and like all Elven groups that survived as Elves after the sundering, learnt from the mistakes of reckless use of magic carried out by Azshara and her lackeys (exception were the blood elves for the brief period in the TFT to TBC period, but they got redeemed), reckless use is different from arcane addiction experienced by the High elves in the period the sunwell was dispersed.

It is to be noted that it is quite possible nightborne can use the nightwell from anywhere like Elves used the Well of Eternity or the High/Blood Elves used Sunwell. It is also to be expected that nightborne are suffused by the energies of the nightwell pretty much like their night elven kin are with the Well of Eternity (notice they have moonwells all over - difference is they avoided using the magic) and the High/blood Elves the Sunwell. Suffusion is not enough for the nightborne though, they must physically ingest arcwine or risk that horrible fate.

Note: It is quite possible the nightborne only discovered this effect of the Nightwell on them recently once the shield came down, the resistance led by Thalyssra has tried but so far unsuccessful at reversing the state of Withered or healing the corruption. I will hazard a guess that it may take the Priesthood of Elune and druids from the main night elf group to cleanse the corruption similar to how the naaru and shattari helped the Sunwell. Afterall, the night elf group have been cleansing moonwells and arcane fonts for 10k years by calling on Elune and the harmony of nature in the land (i.e. Azeroth's Soul).

Another piece of trivia:

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• Ravencrest, Jarod Shadowsong and Maiev also come from Suramar region. In fact... the majority of the sundering survivors that made up the night elf group are actually from Suramar, as they marched from the City and surrounding country to fight the demons. It was here the main resistance to Azshara was born and ultimately succeeded.
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  - This is what the nightborne Ly'leth Lunastre is trying to remind her people of when she asks for our aid in helping the resistance gain more supporters in the city.
  

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• Also it will make for one hell of reunion after this debacle ends. Can you imagine Shandris might
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• actually find family members, or any of the great night elven heroes would have relatives amongst the nightborne who have also been the same generation alive since the sundering. Thalyssra could be Maiev's cousin or sister she never knew she had. Or Oculeth or Valtrois related to the Whisperwinds. What if Elisandre and Tyrande were related? We know priests give up all former associations, and the highborne call Tyrande "Lady Tyrande" was she part of a highborne family before accepting the call of the priesthood? Alternatively as often happened in night elf society, Azshara would raise those she found with extraordinary talent, Elisandre could have been raised, while the rest of her family, though her family were not.
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What is for sure, blizzard could do some really interesting stuff for this group, by making them from Suramar, and having some of the nightborne gone all legion and some fighting the legion in a resistance, makes for an interesting tale.