Selûnarra

Selûnarra was also known as Opus, and was a surviving Netherese city whose patron was Selûne. The city survived the phaerimms' magical assaults by being transported to the Gates of the Moon, Selûne's realm in the Astral Sea, in the Year of the Sundered Webs (-339 DR).

Opus stood in stark contrast to the other enclaves of Netheril. Where a majority of the archwizards opened up schools for magical study to increase the ranks of spellcasters, Opus instead opened up colleges, universities, and other storehouses of knowledge. Where other floating cities had gladiatorial arenas, magical spell duels, and other barbarous acts, Opus established theaters and libraries.

History
Opus was established in -1926 DR by the mentalist Chever, who spent most of his time trying to acquire knowledge after creating his contact other plane spell. It finally cost him his life in -1899 DR, when repeated contacts with an extraplanar being drove him insane and he leaped into a sphere of annihilation. Other arcanists quickly assumed the mantle of leadership, and Opus continued to produce some of the best bards, musicians, poets, and scholars ever known in Netheril.

Age of Discovery (-1205 DR to -697 DR)
Opus soon became a place where the well-to-do of Netheril visited to witness a play, hear one of Netheril's famous bards speak of the barbarian tribes living on the surface, or just experience the true culture of Netheril. As archwizards experimented with abundant metals for magical item creation and the people discovered new veins of gold and silver, life in Opus continued along the scholarly path set before it so many centuries before by Chever.

The Shadowed Age (-696 DR to -340 DR)
The archwizard of Opus, Lady Arilain, discovered that Karsus was creating an ultra-powerful spell in -341 DR. Warning the other leaders of the Opus Enclave, she went to confront Karsus about his avatar spell and was never heard from again.

The Fall and Beyond (-339 DR onwards)
It was widely believed that the city of Opus was spared the destruction of Netheril's cities by divining the effects of Karsus's avatar spell and evacuating mere moments before magic failed. The truth behind their salvation was somewhat hazy, however, and other sources stated that the goddess Selûne personally delivered them from destruction.

In fact, despite being so concerned of celestial matters, they spare some time to spy on the Shadovar and their "conquered" realms. It was also rumored that in one way or another they helped a few Harpers in battling the Shadovar.

Following the Time of Troubles and the battle which took place in Waterdeep between the avatars of Shar and Selûne, an artifact known as the Eye of Selûne was left with Kyriani Agrivar, half-drow owner of the tavern Selûne's Smile. The artifact, which had the power to temporarily open portals to other planes, was eventually revealed by the goddess to be intended for a special ceremony known as the Ritual of the Waxing Moon. If it was performed correctly at Elaz'had, a site near the Sword of Anauroch, a portal would open that would summon Selûnarra back from the Gates of the Moon so as to combat the shades of Thultanthar. But apparently the correct time and manner of this ceremony was never discovered, since such an event never took place.