Denver International Airport is the main airport serving Denver, Colorado, USA, and is one of the largest and busiest airports in the world by land area. It is located about 40 km (25 miles) northeast of downtown Denver, making it quite far from the city compared to many major airports. DEN opened in 1995, replacing the older Stapleton Airport. It was designed to handle large future growth and now serves as a major aviation hub in the United States, especially for flights across North America.