 The platform is broad and four of the stairs from it led to a large mezzanine from which two exits led into the airport terminal building.This was the world's first direct airport-underground railway connection.However, the airport was rebuilt in the 1930s, both because it proved too small and because part of Hitler's plan for converting Berlin into Welthauptstadt Germania was for the main entrance to the airport to be aligned with the triumphal arch on the North-South Axis.