This website is mainly based in the time period directly after The Empire Strikes Back, around the beginning of Shadows of the Empire. There are some areas of this site that are based on different timeframes.
The Galactic Museum is based in the time period when Wedge Antilles and members of Rogue Squadron visited it in Wedges Gamble, 3 years after Return of the Jedi.
The Star Tours Terminal is based around the time before A New Hope, when Alderaan was still in existence.
The Imperial Palace, Monument Plaza, Coruscant Metropolitan Area, Calocour Heights, Invisec, Water Pipelines, and Sky Dome Botanical Gardens are not based in any time period.