Denver International Airport (IATA: DEN), often called DIA, is the largest airport in the United States- by land area, not passenger volume. It covers a whopping 53 square miles. One of it's runways is the longest public-use runway in the US. It has been voted Best Airport in North America by Business Traveller Magazine multiple times, and is the only airport in the United States to have designed and implemented an ISO 14001-certified environmental management system that covers the entire airport.
The airport's distinctive tensile fibregalss roof is designed to resemble the snow-capped Rocky Mountains in winter, and there are many pieces of art and sculptures housed within DIA. This includes the 32 foot tall 'Mustang' which has attracted media attention and mixed reviews.
There are 2 terminals, Jeppeson East and Jeppeson West.
Here are some of the major Airlines that service Denver International Airport:
The above mentioned information is taken from: http://en.wikipedia.org/wiki/Denver_International_Airport