Welcome to Air Force One... and get ready for some changes.

In the summer of 2018, the U.S. Air Force and Boeing announced they had finalized a contract for the acquisition of two 747-8 aircraft that will eventually serve as the new Air Force One fleet.

The planes, which are expected to be delivered in 2024, will undergo a thorough design review and will be modified to meet the very specific needs of the president of the United States. The program will cost tax payers $3.9 billion.

Join us for a photo tour of this most important plane.

You've seen the photos of presidents climbing the stairs to board Air Force One, but did you know that there are actually two entrances to this plane?

The president, his family and special guests use the front entrance here, near the nose of the plane. Journalists board the plane in the rear.

Here, journalists walk to board in the rear as they travel with the president and first lady to Florida and Georgia to view damage from Hurricane Michael.

The press sits in this area of the plane.

President Trump spoke to reporters on Air Force One during the Super Bowl on February 3, 2019.

Air Force One's 4,000-square-foot interior has a reported 85 telephones and numerous televisions.

President Trump said in a 2018 press conference, "Air Force One has about 20 televisions."

This helicopter, known as Marine One, is often used to transport presidents and their guests to and from Joint Base Andrews in Maryland, where Air Force One parks when not in use.

The 232-foot long aircraft features four jet engines, each with 56,700 pounds of thrust. It has a max speed of 630 miles per hour (Mach 0.92) and can fly as high as 45,100 feet. Its range is 7,800 statute miles, though it can be refueled in-air in case of emergency.

Here, the plane flies at a low altitude over the Statue of Liberty on April 27, 2009 for a controversial photo op.

The Air Mobility Command's 89th Airlift Wing of the U.S. Air Force currently maintains two identical Boeing 747-200B planes at Joint Base Andrews, Maryland for presidential use: SAM 28000 and SAM 29000. One is always ready, even when the other is in maintenance.

In this March 20, 2016 photo, Air Force One departs Joint Base Andrews for President Obama's historic trip to Cuba.

The most important spaces aboard Air Force One are located near the president's entrance in the front of the plane.

That's where you'll find the president's private office. The office was upgraded after the September 11, 2001 terror attacks with the telecommunications equipment necessary to address the nation from the skies.

The president's office aboard Air Force One is surprisingly spacious to accommodate important meetings such as this one involving President Barack Obama, Secretary of State John Kerry and National Security Advisor Susan Rice.

The president's private suite, located in the nose of the plane, has foldable couches and a private bathroom. The southwestern decor theme seen here was designed by Nancy Reagan.

In this photo, George W. Bush and his Chief of Staff Andrew Card hold a discussion in the hours immediately following the September 11 terrorist attacks.

Adjacent to the president's office, near the entrance to the plane, is the Air Force One medical compartment. Always staffed with a nurse, it has a supply of blood, drugs and a defibrillator.

In this photo, nurse Cindy Wright gives President George W. Bush a massage shortly after the attacks of 9/11.

With a total of 4,000 square feet of interior space, Air Force One offers the president a lot more room than he'd get on a commercial airliner. There are even couches and phones in the hallways, allowing for impromptu meetings.

Down the hallway toward the back of the plane is the senior staff room. There a president can hold meetings and discuss policy with staffers.

In this photo dated Sept. 9, 2012, President Barack Obama and Deputy Chief of Staff for Operations Alyssa Mastromonaco listen to a conversation en route to Joint Base Andrews in Maryland.

Larger meetings are held here in the conference room, adjacent to the senior staff room. It often doubles as a dining room.

In this April 5, 2009 photo, President Obama meets with aides while en route to Ankara, Turkey.

The elaborate meals served aboard Air Force One are prepared inside a special kitchen at Joint Base Andrews. Each entree is vacuum sealed and frozen on the ground; the cooking process is completed on stoves, ovens and microwaves in the plane's galley kitchen.

The president can order just about any meal he'd like. The only catch: Because there's no fryer on the plane, the fries served up by Air Force One tend to be a bit soggy.

Past the conference room is the Air Force One staff room. There are 85 phone lines and 19 televisions on each of the two identical planes, allowing the White House to stay in touch with events on the ground.

Members of Congress and other invitees of the president sit here, in Air Force One's guest section. It's the front-most seating section for security reasons: Secret Service allows passengers to move freely toward the rear while in flight, but guests are never allowed to walk forward past their own seat.

Here, President Obama shares a laugh with Sen. Patrick Leahy (D-VT) and wife Marcelle Leahy on March 30, 2012.

Traveling press are seated in the very back. They don't fly for free: News organizations must reimburse the government for the cost of travel.

Occasionally, the president will walk back to the press section to talk and answer questions, as President Trump did while on the ground at Andrews Air Force Base on February 3, 2017.

Here, President Trump speaks to the press with first lady Melania Trump during a February 10, 2017 flight on Air Force One bound for the president's Mar-a-Lago resort in Florida.

Retired Air Force One planes are a hot-ticket item.

Following its retirement, SAM 27000, the plane used by Presidents Nixon through George W. Bush, was disassembled and shipped to the Ronald Reagan Presidential Library in Simi Valley, California, as seen here on June 21, 2003.

These days, you can explore the inside of SAM 27000 inside The Air Force One Pavilion at the Ronald Reagan Presidential Library. The plane was famously used as a backdrop during the September 2015 Republican presidential debate held at the library.

Here, President Reagan and first lady Nancy Reagan share a moment together in the Air Force One state room on a trip to the United Kingdom on June 4, 1984.

The term "Air Force One" gained popularity with the introduction of SAM 26000, a Boeing 707 obtained for use by President John F. Kennedy. It was replaced by President Richard Nixon in 1972.

Here, President Kennedy arrives in Alameda, California on March 23, 1962.

This image -- arguably the most important Air Force One photo ever taken -- was taken at 2:38 p.m. on November 22, 1963 in Dallas, immediately after the assassination of President Kennedy.

White House photographer Cecil W. Stoughton has said he found the act of photographing the newly widowed Jacqueline Kennedy "tasteless," but he felt compelled to capture the swearing in of President Lyndon Johnson out of respect for U.S. history.

President Dwight Eisenhower's gleaming Lockheed Constellation, named Columbine II, was the first plane to officially carry the Air Force One call sign. It was in service from 1953-4, when it was replaced by the Columbine III.

In this photo, Dwight and Mamie Eisenhower exit the Columbine II in 1953.

The official presidential plane hasn't always been so large and luxurious. President Truman's plane, The Independence, is a military version of the Douglas DC-6.

The Independence was commissioned in July 1947. It was retired to the National Museum of the United States Air Force in Dayton, Ohio in 1965.

Truman's Independence aircraft was cramped, offering space for just 25 passengers and a crew of nine. Today, President Trump's Air Force One can carry up to 76 passengers, with a crew of 26.

Franklin D. Roosevelt became the first American president to fly while in office on January 11, 1943, to attend the Casablanca Conference with British Prime Minister Winston Churchill. He made the risky wartime trip inside the Dixie Clipper, a Boeing 314, because German U-boats made travel by sea even more dangerous.

Here, President Roosevelt celebrates his 61st birthday on the Dixie Clipper on January 30, 1943, while roughly 8,000 feet above Haiti.