Official LEGO stores offer the opportunity to fill a cup (small or large) with LEGO elements from a wall with shelves, usually near the back at the store. These are called PAB walls (Pick A Brick)
This is often one of the cheapest ways to purchase LEGO elements.
However, the size of the wall and hence the size of the selection, differs from store to store.
I was wondering, which stores have the largest wall ? In Europe I think it is the one at Disneyland Paris, but I could be mistaken. I'm also interested in other countries/continents...