Antique French Map 1600's-1700's

Got lucky on this piece as a customer was going through her storage lot, she was throwing into the dumpster some frames and furniture pieces. She was about to pitch this in when I asked for it. After doing some research I know it's french but don't have any idea what it says, or what the map shows, anyone knows french and can interpret it would be appreciated.
This is the Heading......
Evesché de Luçon dedié a Monseigneur Messire Henry de Barrillon, evesque et baron de Luçon / par G. Sanson
I know the cartographer is G. Sanson
I know with the fold in the map this was removed from a book. Much past that I need help.