The most important structure in an airport is The runway.
runway is a defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft.
Before, runways were grasy fled and later. Runways were made of concrete or a natural surface grass, dirt, gravel it was because runway is importantt a defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft. The problem of runways was muddly in rainy weather