The buildings of the Zaventem airport were designed in 1956-1958 by Maxime Brunfaut, Georges Bontinck and Jos Moutschen. It was initially estimated that it should have a maximum capacity of 6 million passagers per year. The 1950s were characterised by an uncurbed belief in technological progress. This was translated into the architecture by using such materials as aluminium, concrete, steel, and glass. The transit hall was intended as a striking feature with a space of a 100m long, 55m wide and 18m high, covered with a curved roof structure out of aluminium. Over the years, expansions and adjustments were made, leading to the loss of much of the original design. In 1994, Pier B was put into use so that 21 million passengers could be handled annually. Pier A was opened in 2002 to ensure a better flow and increased passenger comfort, processing another 25 million passengers annually.