Air Force One, the presidential plane, is able to carry the president and 100 advisers and journalists across the country or around the world.

To create Air Force One, engineers started with two 747-200Bs. There are two identical Air Force Ones, so the President can fly even when one of the planes needs maintenance. These planes are gigantic - more than 200 feet long with three levels inside.

Inside, Air Force One looks nothing like a normal 747 operated by commercial airlines. Instead of installing rows of seats, engineers designed a 4,000-square-foot deluxe flying office and hotel for the United States president.

There are three ways to board Air Force One. The president and dignitaries typically get on and off the plane using the main entrance on the middle level. Staff and crew use a door on the lower level, just underneath the main entrance. And journalists use a door on the lower level at the back of the plane. Let's assume that you board the jet with the president. As you walk through the door you are standing in a small foyer area on the middle deck.

Toward the nose of the plane is the presidential suite. There is a spacious office for the president, a medical room, a private bathroom and a bedroom. The office has a large desk and comfortable executive seating. The medical room can handle nearly any emergency. There is a surgeon who flies with the president, and the medical room includes a complete pharmacy, X-ray equipment, emergency equipment and even an operating table.

There is a galley kitchen that is able to serve 100 people at a time, and freezers on the lower level hold up to 2,000 meals. Just past the galley is a large conference room that takes up nearly the entire width of the plane. It comes complete with a large conference table, televisions and computers and sectional seating along the walls. This room can comfortably accommodate 20 people.

Past the conference room is a workroom with tables and chairs for smaller meetings. Beyond that is the rear seating area and restroom. This seating area is set up with rows of seats like you might find in a first-class cabin of a commercial jet.

The upper deck is smaller and contains the airplane's cockpit, a second galley and lounge area and a communication room filled with equipment and computers. This room makes it possible for the president to talk to anyone in the world and to communicate securely with the Pentagon.

Air Force One has a number of features not available on your normal 747. For example, Air Force One can handle aerial refueling so that, in an emergency, the plane does not have to land. The plane also has electronic countermeasures equipment that can help jam enemy radar. It also has a flare system that can outwit heat-seeking missiles.

The Air Force is considering replacing Air Force One. It has been in service since the 1990s. The Air Force could replace it with the new 747s, or possibly the A380 - currently the largest commercial plane available.