Here is the largest photo on this forum - 103 megapixels (16402px x 6301px), and able to print more than 5 feet wide by 2 feet tall at 300 ppi.
Multiple shots, auto-stitched in Photoshop CS6. Nikon D600 with a 24-120mm f/4 VR on tripod.
Full Size: http://farm8.staticflickr.com/7439/9...bb5548_o_d.jpg

Small Size: