Thelas En Opon

Purpose / Function

Most scholars agree that the purpose of the whole contraption was to be a calendar, with the tablet at the centre being what decoded the movements of the sun and stars, however none can understand the intricacy and lengths gone through for such a thing. For even modern mages can assess the time and season to a reasonable degree of accuracy with the simplest cantrip, so such an advanced civilization could surely have created a simpler and easier calendar system than this huge undertaking. 
And why has only this survived the ages where the surrounding settlement has fallen to rubble?

Architecture

A huge dome-shaped building of metal and glass, this ancient machine stands in the middle of the ruins of a city whose name has been lost to time, though the name of the dome itself remains carved into the archway that marks its entrance. The glass and moving gears refract the light in perfect unison with the movements of the sun, moon and other celestial bodies and concentrates it upon an indecipherable tablet in the centre of the dome. The interior of the building houses a bountiful garden in constant flux. It's interior climate changes with the season, bearing fruits and flowers of the time of year.

History

The first to (re)discover the Dome of Seasons was a Durishani explorer named Samaya Devar, who promptly became obsessed with it and spent the rest of her life trying to figure out the mechanics of the thing. She shared her knowledge only with her son Ayal, but he did not share her wonder at it, and he published her findings as soon as she passed so that he could wash his hands of the endeavour and let other scholars puzzle it out. These notes, named Consider Thelas have become invaluable for any wishing to study the building's mechanisms and many have even made their own additions to the work.

Alternative Names

The Dome of Seasons