BERLIN — As rents rise in many of the world’s major cities, it’s almost unheard of to find any unused space. But in the heart of Berlin sits an empty area so massive that it’s the size of an entire country.

Tempelhof Field was once the world’s largest airport, the same size as the principality of Monaco. While developers have long coveted the expanse of land, Berliners voted in 2014 to keep it untouched. Instead of apartment blocks, the space hosts everything from kite-surfers and barbecue fans to beer gardens and a baseball field. Now the city has approved a plan to invest nearly $370 million dollars to turn the old terminal building into an event space and hub for start-ups and businesses.

It’s yet another rebirth for a site that has morphed over the decades from a symbol of Nazi power to an acrobatic air circus, a concentration camp, a U.S. air base, Germany’s largest refugee shelter, a concert venue and other operations.

The Nazis built Tempelhof in 1936, intending it to be the world’s biggest building and an entryway to Hitler’s future world capital, “Germania.” Hitler began sketching the plans in 1933, giving the terminal its arced shape and vast dimensions. “There’s no real style, but an expression of immovability, solidness and timelessness that’s typical of the Nazi era,” said Wolfgang Schache, an architectural historian who has been studying and writing about Tempelhof for more than three decades.

Hitler eventually commissioned architect Ernst Sagebiel to finish planning Tempelhof, but the project took a back seat to Hitler’s main priority: committing resources to prepare for war. To this day, sections of the airport are still incomplete.

After the war, Tempelhof became a crucial hub during the Berlin Airlift. After the Soviets cut off ground access to West Berlin in 1948, the Americans, British, French and other allies operated an around-the-clock schedule of cargo flights that provided the city with food and supplies for nearly a year.

Inside the airport’s main hall, a mural memorializes the “candy bombers” — American airmen who used to make miniature parachutes out of matchboxes, fill them with candies and throw them out of planes to children in West Berlin. Outside, an American plane used during the airlift still rests on the field.

Tempelhof continued to serve as both a U.S. military airfield and a commercial airport throughout the Cold War — and well afterward. While traffic to the airport dwindled after the city was reunited and its other airports expanded, Tempelhof did not fully close until 2008.

Rather than use the space for housing construction, Berliners voted to keep it a public space for recreational activities.

In 2015, during the height of the refugee crisis, hangars were turned into emergency shelters for refugees. By the end of the year, nearly 2,500 refugees had moved in. Some lived in the shelter for up to three years without any private space — or certainty about whether they would be deported.

Parwiz Shafizad, a former journalist from Afghanistan who fled the Taliban in 2015, lived in one of Tempelhof’s hangars for more than a year. “Imagine in one hangar, there are more than 500 people, he said. “They say one word, and it makes more than 500 echoes because the ceilings and walls are made of iron.” Shafizad said the hangars led to a host of mental-health issues for the refugees who lived there.

In December 2017, refugees were moved from the hangars to to a container village on the airfield made up of so-called “Tempohomes,” modular containers that are fenced off from the rest of the field. There are 440 people currently living there, waiting to find out whether they will be granted asylum and relocated to permanent housing — or be forced to return to their home countries. Now the city is hoping to refashion Tempelhof once again, this time as a creative hub. “Our goal is to turn the airport into a place for art, culture, creative industries and experiments,” said Tempelhof spokeswoman Irina Dahne. “We want to be the destination where new creative enterprises want to be located, and feel they must be a part of.”