Complex sentence: Centennial Airport, formerly Arapahoe County Airport, lies adjacent to Centennial but is in unincorporated Arapahoe County; it is not named after the city, as it predates it by over 30 years.
Split into simpler sentences: Centennial Airport, formerly Arapahoe County Airport, lies adjacent to Centennial, but is located in unincorporated Arapahoe County. The airport is not named after the city, as it predates the city by over 30 years.