Berlin is a city full of abandoned buildings with long and troublesome histories. But one building has been through more turmoil than most: Tempelhof Airport.

The colossal airport straddles Neukölln and Tempelhof -- neighbourhoods approximately 4 kilometers, or 2.5 miles, south of the city's centre.

The airport's main building was once one of the largest structures in Europe, and it was crowned "the mother of all airports" by British architect Norman Foster.

Tempelhof has been used to test some of the world's first aircraft, house World War II prisoners, and give the people of West Berlin a vital lifeline to the outside world during the Cold War. It's also been used to film movies such as "The Hunger Games," "The Bourne Supremacy," and "Bridge of Spies," as well as for the occasional illegal rave.

Despite efforts from about 500 protesters and a majority voting in a referendum to keep it open, the airport officially closed on October 30, 2008.

Today, the airport is being used as a massive refugee camp with space for up to 7,000 migrants.

We went on a tour of the airport led by a guide named Celine Gilly:

Tempelhof Airport was built by the Nazis on the site of a much smaller existing airport between 1936 and 1941. It's huge.

​After the Nazis took power, they set about redesigning Berlin. Tempelhof was designed to wow visitors to the new Third Reich capital of Germania. It represents the monumental thinking behind Nazi architecture and it's a landmark in civil engineering.

Today, large parts of the airport are derelict, including the former departures hall.

Long, empty corridors that would have been used by Hitler's henchman and subsequently international passengers now feel eerily quiet.

The Nazi-era terminal is 300,000 square metres when you include the hangars.

Floor-to-ceiling windows were used to let as much light into the airport as possible.

Before the Nazis came to power, Tempelhof was used to test some of the world's first aircraft.

Berliners flocked to the airfield to see early airships and balloons being tested. It was here, for example, that the Humboldt balloon was launched on its maiden voyage on March 1, 1893.

The successful flight inspired several other balloon excursions to study the atmosphere. On each flight, an airship lieutenant assisted numerous professors and doctors.

The Nazis came to power in 1933 and quickly got to work replacing the existing airport (built in several stages from 1923 to 1929) with the larger building that sits there today.

Hitler took a personal interest in Tempelhof's development.

Architect Ernst Sagebiel was commissioned to design the airport in 1935, and construction began the following year. Sagebiel introduced many innovative features that went on to be copied elsewhere including separate levels for passengers and luggage, for example.

The airport has a vast 303-hectare airfield. By way of comparison, Monaco is 200 hectares. Both the airport and the airfield are now owned by the city of Berlin.

The airfield is used by kite surfers, rollerbladers, allotment enthusiasts, artists, cyclists, joggers, jugglers, batton twirlers, and dancers. This month, it was also used for a Forumla E race.

Name an activity, and it's safe to say that someone has probably done it here at some point.

The fact that the site is so widely used by the public today is apt given that it was used by Berliners for picnics and sport long before it housed an airport.

In years gone by, the site has also been used for horse racing and football. BFC Frankfurt was formed at Tempelhof in 1885, and Berliner FC Germania was founded in 1888 and remains Germany's oldest active football club.

Intended to be a statement of Nazi Germany greatness as well as a stage for Hitler to address the masses, the airport was only ever 80% finished. Most of the exterior is complete, but an abundance of work still needs to be done inside, giving it quite a raw feel when you walk around.

A curved roof that extends 40 metres over the airfield is one of Tempelhof's most defining features. It was designed to be almost a mile long and to protect passengers from the weather as they walked to and from their planes.

The canopy-style roof relies on a cantilever system to stop it from collapsing.

Hitler also wanted it to be able to both shelter travellers and accommodate 100,000 people during Luftwaffe air shows and military parades.

But his wish never came true, as the 13 staircase towers designed to take people up to the roof were never finished.

Other things that never came to fruition at Tempelhof include a waterfall, large-scale offices, and a control tower.

Hitler also had even more grandiose plans that involved building a giant stadium around Tempelhof with the potential to accommodate a million people.

Relatively few bombs were dropped on Tempelhof during World War II, so most of the airport remained intact. Why? Though partly because the Nazis protected it with antiaircraft guns, it was also because the Allied forces knew they could use it after the war.

When bombs did fall on Berlin during the war, these air-raid shelters in the depths of Tempelhof would be filled with people.

The shelter rooms still contain original paintings from the war that were designed to distract children from the chaos above.

The shelters were used by factory workers that lived in the surrounding neighbourhood. They contained beds, toilets, food, and other amenities.

Heat marks around window panes show where the building was once on fire. The building is made of limestone, which turns red when it gets too hot. There are also bullet holes across the airport from when the Nazis were fighting the Soviets in 1945.

Ironically, the Nazis never actually used Tempelhof as an airport. During the war they used it as a factory for building combat aircraft and weapons. Several Ju 87 "Stuka" dive bombers were built in the hangars. All of this was done by forced labour.

The Focke-Wulf 189 was a plane used by the Nazis.Wikimedia Commons

The German airline Lufthansa used the labour force for maintenance, mounting radar installations, and repairing aircraft.

The forced labourers were freed by the Red Army in 1945 as World War II came to an end. In July 1945, the Red Army handed the airport over to US forces. After undergoing extensive repairs, the airport came into operation again.

The Americans occupied Tempelhof from 1945 to 1993.

There is a café for refugees at Tempelhof simply called "The Cafe".Business Insider/Sam Shead

The US Air Force built a white radio tower at Tempelhof for surveillance purposes.

Today, the 72-meter tower is used by the German army to monitor flight traffic in and out of the capital, though many Berliners aren't aware of this.

The US Air Force did its best to turn Tempelhof into a serious military base. It set up various training facilities at the airport that have since been abandoned, including this shooting range.

This is a parachute jump training facility.

Inside the airport building, the Americans set up various function rooms, such as this one with a bar/kitchen area.

American pilots would come here to relax. There would have been a bar, snacks, a pool table, a bowling alley, and a disco area.

Elsewhere at the base, there was a full-size basketball court.

At one point, 2,000 US military personnel were based at Tempelhof. In addition to the basketball court, they had access to baseball pitches, a supermarket, and a cabaret cinema. Some American officers even had their families here.

A posting to Tempelhof was seen as one of the more desirable US military postings, which isn't surprising, given US military personnel were also being sent out to the Middle East and Afghanistan around the same time.

An old US Air Force plane seen under the main Tempelhof sign.

From June 24, 1948, to May 1, 1949, the airport played a key role in the Berlin airlift.

At the end of World War II, the US, British, French, and Soviet military forces divided and occupied Germany. Berlin, which was also divided into occupation zones, was located far inside Soviet-controlled eastern Germany.

There was initially an alliance between the Western Allies and the Soviet Union in Berlin, but on June 24, 1948, the Soviet forces blockaded rail, road, and water access to parts of Berlin that were controlled by the Western Allies.

"The United States and United Kingdom responded by airlifting food and fuel to Berlin from Allied airbases in western Germany," the US Office of The Historian website says. "The crisis ended on May 12, 1949, when Soviet forces lifted the blockade on land access to western Berlin."

Tempelhof was used as the takeoff and landing site for the "raisin bombers" that provided the people of West Berlin with vital supplies, such as food, coal, and medical supplies. They also used mini-parachutes to drop 22 tons of candy for the children of Berlin, which led to their becoming known as the "candy bombers".

A plane landed every minute at Tempelhof, and about 2.3 million tonnes of freight was flown into the divided city, according to The Guardian. Almost 80 pilots died in crashes.

Graffiti inspired by the Berlin airlift can be seen on the homes surrounding Tempelhof.

In 1951, the American occupation forces released the airport for civil and freight traffic.

The airport eventually ended up with many of the things that are commonplace in airports today, such as restaurants.

Tempelhof was then visited by the likes of Marilyn Monroe and Ronald Reagan.

​Reagan visited June 11, 1982, as tensions between East Berlin and West Berlin mounted. He advocated more military power and an arms buildup instead of an easing of tensions.

Retro check-in desks are some of the many relics inside the main departure area.

The car-rental kiosks at Tempelhof look just like the car-rental kiosks found in many of today's modern airports.

The American forces made one or two changes to Tempelhof while they were there.

In 1962, the Americans removed a 5-metre sculpture of an eagle perched on a globe from the main terminal roof and replaced it with radar equipment. The eagle's head now sits outside the terminal building.

Various other "imperial eagle" statues can be seen around the airport.

It feels as if time has stood still in large parts of the airport.

The airport's fire service once used this plane as a practice aircraft. It now provides a unique perch for resting birds such as hawks, according to The Guardian.

Tempelhof's capacity was stretched to the limit in the 1960s, and operations at Tempelhof were suspended after the construction of Tegel airport in West Berlin's French sector in 1975.

​In 1990, after the fall of the Berlin Wall, Tempelhof started to operate domestic flights once again.

In 1993, the US Air Force handed the airport over to the Berliner Flughafengesellschaft, and it was used on and off for commercial purposes until November 2008.

In 1995, Tempelhof became a listed building, meaning it can't be torn down.

Tempelhof's future has been a matter of debate ever since it stopped acting as an airport.

​In 2011, city planners wanted to build commercial areas and offices, 4,700 homes, and a large public library, according to The Guardian.

The planners said they would take up no more than 25% of the site and stressed that there would be a focus on social housing, while also leaving 230 hectares free in the middle.

But locals were skeptical, and the 100% Tempelhofer Feld initiative gained enough signatures to force the city to hold a referendum.

In May 2014, after years of fighting, 64.3% of eligible voters chose to keep the Tempelhof site unchanged. That means the Tempelhof park has to stay as it is until 2024.

The Tempelhof Conservation Act prohibits construction anywhere on the former airfield and ensures only limited development.

While the buildings and the airfield remain largely unchanged, more than 100 businesses are based out of Tempelhof today.

The main tenants of Tempelhof are the Polizei, or police. They occupy approximately 46,000 square meters (about 15% of the total) and have been renting since 1951, which is when the US military began leasing out parts of the building. In addition to the Polizei, the airport is also home to a kindergarten and a dancing school.

"Berlin is a pioneer in re-using buildings that were left over after the division of the city," Tempelhof project chief Gerhard Steindorf told Abandoned Berlin, using the techno club Tresor as an example of a successful metamorphosis. "It's a party city."

Tempelhof is also home to Germany's largest refugee shelter. There were 3,000 refugees from countries like Iraq and Syria living in a hangar at one point, but that number has fallen to about 600 as German authorities have relocated many of them, while others have returned home. There is enough space in the hangar for 7,000 refugees.

​The refugees live in cubicle-type structures with little privacy. It's also noisy inside, and the lights are either on or off for everyone. In many ways, living in the refugee camp is like living in a train station.

While the conditions aren't luxurious, refugees do have access to Wi-Fi, which means they can use apps like the German language app Daheim if they own a cheap Android smartphone.

The shelter is closed to the public, but there is a refugee cafe in Hanger 1 the public can visit and provide German lessons.

Some refugees are being moved into modular homes just outside the hangar.

The white tent on the airfield is being used as a school for refugee children, who are encouraged to take part in sports and other activities.

Tempelhof remains a unique place.

"The plan is to develop the park with direct community involvement, but there are restrictions on what can be done," Tempelhof project chief Gerhard Steindorf said. "New buildings are out of the question."

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