With some themes, iPhoto can fill an entire two-page spread with a single photo—it’s a dramatic way to highlight a scenic vista or a panorama. In the Layout pane, choose the Spread option. Many themes have several variations.
Tip: Keep in mind that part of the photo will get lost in the gutter between the left and right pages. By zooming in a bit and repositioning the photo, you can often make sure nothing important gets lost.