Well, using google maps, the pyramids are at (very, very roughly) 30 lat, 30 long. If you take the parallel from the west coast of africa to the east coast of Saudi Arabia, you're going from -10 long to 48 long, so across 58 degrees of longitude. And from North to South, the meridian would go from 31 lat to -30 lat, 61 degrees of latitude. My first guess for an intersection with longer lines would go from the west coast of France, to the east coast of Russia, near the the sea of ohkotsk, which is -4 long to 139 long, or 143 degrees of longitude, which is longer than the two pyramid intersections put together.

Now, this is assuming that lakes don't count. I don't know if any of those three lines have lakes crossing them, but odds are they do. Rivers obviously don't count, or the Nile would probably mess up the Pyramid lines immediately.