First-time visitors to the vast open area in the middle of Berlin often need a minute to take it all in. Stretching out before their eyes is a disused airfield that was constructed by the Nazis in the German capital’s Tempelhof district long ago. After the former airport was shut down in 2008, the site was converted into the city’s largest public park. Where once planes took off, skaters and cyclists now speed along the two runways. Due to its vastness, Tempelholfer Feld (Tempelhofer Field) as the locals call it, is a popular spot for flying kites. Designated areas for barbecuing, which is pro…