In Asimov's original
Galactic Empire and
Foundation novels, Trantor was located at the exact center of the
Galaxy. This example of
central place theory1 taken to extremes was an important part of the mythical image Asimov was trying to construct, and figured prominently in the plot
2.
The impossibility of Trantor being in this location was eventually pointed out to Asimov, who, when he began the commerical milking of his series with
Foundation's Edge, moved Trantor to the galactic disk, just ouside the Core.
This seems like a shame to me.
1Who said Isaac Asimov wasn't a geographer?
2I'm tying to be careful here, OK?