Monthan Air Force Base near Tucson, Arizona. The site is currently called the 309th Aerospace Maintenance and Regeneration Group. There have been planes stored at the base since 1945, when they took possession of a number of Army Air Corps B-29s and C-47s following the end of WWII. The site was chosen for its low humidity and high altitude, which slows the rate of decay down amazingly. With little to no precipitation, these airframes can sit outside in the elements for decades with only minor damage. The alkali soil also cuts down on the corrosion and rust of the steel parts. AMARG also is fairly unique among military bases in that it makes more money than it costs to run the base. For every $1 the federal government spends operating the facility, it saves or produces $11 from harvesting spare parts and selling off inventory.
If you take a closer look at the pic above, you can clearly distinguish many different types of aircraft. There are dozens of B-52s, some with their wings cut off so that the Soviets could verify their retirement as a part of arms treaties. Their is a line of B-1 bombers down the left center of the lower half, to the right are some assorted helicopters, mostly UH-1 Hueys and CH-47s . In the top section, you can see some Navy aircraft, including the F-14 Tomcat in the center and some E-2C Hawkeyes in the bottom, near the bisecting road with F-111 Aardvarks to the right.
The site is massive, spread out over 2,600 acres, and it has over 4,400 aircraft in its inventory. This includes hundreds of B-52s and over 700 F4 Phantoms. While many of the planes and helicopters at AMARG will never fly again, some are stored for possible future use. For example, from 2006 to 2008, five mothballed CH-53Es have been reinstated from AMARG due to combat losses in the War on Terror. From time to time, older aircraft are activated to replace others lost in accidents, combat, or those that have reached their maximum number of flight hours. With modern aircraft, the avionics, radars, targeting pods, etc. can cost as much as the airframe its self, so this makes good sense. There are four categories of aircraft at the Boneyard. "Parts Reclamation" are aircraft that are kept for parts to keep others of their type in flying condition. "Excess of Department of Defense Needs" are aircraft awaiting sale, mostly to foreign Air Forces, either whole, or in parts. "Long Term" storage is for aircraft that are being kept intact for possible future use. Many of these planes can be restored to flying condition in a matter of hours or days. The last category is "Flying Hold", which is for aircraft that are in a shorter term storage than the long term. Some aircraft have been rebuilt for use as remotely operated flying targets for Air Force and Navy fighter aircraft.
You can see how potentially useful airframes like these Hueys, Phantoms and Warthogs are protected from the elements as much as possible. Aircraft entering storage are carefully preserved. First, the plane is disarmed. Then, all classified equipment, ejection seats and so forth is removed. The aircraft is emptied of all fuel and the lines are filled with light oil and drained to form a protective barrier in the tanks and lines. To protect the aircraft from dust, high temperatures and and sun damage, it is tightly sealed. Sometimes this means putting up a sun shield over the windows and other times the airframe is wrapped in white plastic or even sealed with a vinyl compound called spraylat. Then it is towed to its storage position. Just like in the end of Raiders of the Lost Ark.
I have read that a number of Vietnam-era jets (probably F4 Phantoms) have been sold to Turkey in the last several years. While the F4 will never be a front line fighter aircraft again, it can serve well as a light tactical bomber or even stand in as a dedicated close air support platform. And if you have the right friends at the Pentagon, you can probably get them for a song. Congress has oversight on what types or aircraft and parts can be sold to whom, which is why the F-14s at AMARG will likely sit there until the desert swallows them up. The F-14 is currently only in service in the Air Force of Iran so the Government is not selling any Tomcat parts to anyone. (After they accidentally sold some spare parts to Iranian agents. Whoops.)