90,000 BBY

90,000 Before the Battle of Yavin, also known as 86,347 Before the Treaty of Coruscant, was a year during the Pre-Republic era. Approximately this year, on the planet of Coruscant, Galactic City stood as a many tiered settlement. This was the groundwork for the hundreds of levels, which stretched kilometers from the surface, that would exist by 11 ABY.

Behind the scenes
The year 90,000 BBY was mentioned in The Essential Atlas (2009). Coruscant had been established as having many levels of architecture for years before this release, as established in Dark Apprentice (1994) by Kevin J. Anderson. The Atlas was the first source to provide any quantitative age for these structures.