This is how an airplane looks with no seats installed
It is amazing how airplanes can look so large from the outside but so small from the inside. The cabin is usually so crammed with seats that it is hard to judge the actual scale of the aircraft properly. Check out how the interior of an airplane looks without seats. This is surprisingly rather roomy.
This is a photo of a Boeing 787 before the airline installed any of its seats inside. There is so much room it could almost serve as a ballroom. Just think about it: All that space, and it is still impossible to stretch your legs properly when traveling in coach.