I don't have very much on Skywatch - but here is the stuff I have collected so far.
Overview. (from the Newhaven page)
Skywatch is an ancient site - believed to have been used for studying the sky and the stars. In the past it has been a stronghold for House Surtova, but it became a stronghold for the Aldori Swordlords. Eventually they were burnt out and a new city built as a stronghold for House Rogarvia. However of the day of 'The Vanishing' the city sealed its gates and there has been no communication with it since.
Sealed its gates, can be considered a bit of an understatement, - people have tried flying in, tunnelling in, planar travel and all sorts. Even sending fetch's and scrying spells. All have failed miserably.
History (from the web)
The Observatory
The observatory is older than any known settlement in the region, and its origins and purpose remain a mystery. The ancient structure was obviously built to accommodate beings much larger than humans, and it has been preserved through the ages by powerful magic. Who built the ancient structure and why is as yet unknown.[1]
Early History
The city of Skywatch began as a simple outpost, around the observatory during the early years of Issia's history. This fortification was overtaken by the Aldori during Issia's constant war with neighboring Rostland, and it served as an Aldori stronghold even after Choral the Conqueror brought both nations to their knees and united them under his rule.[1]
A few years later, however, Choral and his red dragon allies put an end to the Aldori separatists at Skywatch, burning the fortress to the ground. Choral then showed a great deal of interest in the observatory and began excavating and researching the mysterious observatory after the Aldori defeat and built the modern city of Skywatch atop the original settlement's burnt ruins. After his departure, House Rogarvia took over the endeavour on Choral's behalf. The goals and any results from this examination of the observatory are unknown.[1]
Recent History
Strangely, on the same day in 4699 AR that every member of House Rogarvia disappeared, Skywatch sealed itself off from all outsiders, including supply caravans. Since that day, no message sent to Skywatch has received a response and even powerful divination magic fails to penetrate the city's ancient walls.[1]
Skywatch (from the module)
High in the northern Icerime Peaks is a city built around an ancient observatory discovered by the Surtovas centuries ago in the early days of Issia. In spite of its apparent age, the observatory is perfectly preserved, maintained by a powerful, lingering magic. The same night House Rogarvia vanished, Skywatch sealed its gates, and the walled city has allowed no one to enter or leave since, not even couriers or supply caravans. Messages and envoys sent to Skywatch have been ignored and none are known to have left. Even divination magic cannot penetrate its walls to discover what is going on within, or even if anyone there is still alive.
