In terms of stations? None of the TGV stations on dedicated HS lines (that I know of) are actually in town -- the only exception I know of is Lille, where the station is on HS line in town.  The TGV stops in the bigger cities : Paris, Lyon, Marseille, etc -- use historical stations and share the rails with normal trains.

The stations that serve smaller towns -- Avignon, Valence, Mâcon etc -- are new build, at least a couple of km out of town, generally not even in walking distance of the nearest village I suspect the network was designed by the taxi drivers' trade union.

hmmm I guess that means the answer is Lille (around 1 million people). Any better answers?

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