The main part of the store is situated between Boulevard Haussmann and Rue De Provence a short walk from the Opera.  From the outside there is not much to see and you might even be put off by the stalls outside selling products at 5 and 10 Euros but don’t be.  Go inside Galeries Lafayette and be surprise by the amazing glass roof that spans the main shopping area.  It reminds one of Liberties in London with the balconies all around.  I am told that at Christmas this central area is filled with an enormous tree and they go overboard with wooing the shoppers with samples to try in the food halls.
For those not shopping at Christmas time it is still worth going to the food halls but remember to go hungry.  The delight of the store is the ability not only to by the food at the counters but also to sit around café style and try it.  This makes it an ideal experience for those who are not self catering but wish to experience more closely how the local Parisian will eat.
I am reliably informed that the clothes, shoes and other bits that girls love is exceptionally well catered for especially when it comes to bargain hunting time.  At the end of which with all the money saved you will probably feel justified in relaxing over a glass of champagne at Bubbles Bar or their Wine bar beside the Wine Cellar.
Galeries Lafayette Roof Light