By 1954, Christiansen's son, Godtfred, had become the junior managing director of the Lego Group. It was his conversation with an overseas buyer that led to the idea of a toy system. Godtfred saw the immense potential in Lego bricks to become a system for creative play, but the bricks still had some problems from a technical standpoint: their locking ability was limited and they were not versatile. In 1958, the modern brick design was developed; it took five years to find the right material for it, ABS (acrylonitrile butadiene styrene) polymer. The modern Lego brick design was patented on 28 January 1958.
The remainder of the build is the control tower and terminal building. First there is a metal detector screener leading to the waiting/secure area of the airport, which seems taller than it needs to be for the minifigures. I think the same effect could have been made with half the height, except that would not allow for an impressive height for the overall tower. However it does seem to be similar to many modern airports with the high ceilings. This area also seems to be someplace to check luggage as evidenced by the rather nifty conveyor belt that comes in a full part. The moving parts of the set include a revolving door (a very tall one, for the first floor) that leads from the secure area of the airport out to the tarmac, and of course the conveyor belt.