are utilized by all non-United flights as well as a limited number of United Express flights. Concourse A has 47 gates, located in the eastern half of the north midfield terminal. It consists of a permanent ground-level set of gates designed for small planes and Unted Express flights, and several former Concourse B gates. The concourse is primarily used for international flights. Air France and KLM have a lounge opposite gate A19, Etihad Airways operates a First and Business Class lounge across from gate A15, and Virgin Atlantic has a Clubhouse lounge adjacent to gate A31. Concourse A's AeroTrain station is located between gates A6 and A14. Concourse B has 28 gates, located in the western half of the terminal. It is the first of the permanent elevated midfield concourses. Originally constructed in 1998 and designed by Skidmore, Owings & Merrill and Hellmuth, Obata and Kassabaum, the B concourse contained 20 gates. In 2003, 4 additional gates were added to concourse B, followed by a 15-gate expansion in 2008. In addition to the AeroTrain station located between gates B51 and B62, Concourse B also has an underground walkway to connect it to the main terminal. Concourse B is used by some international carriers, and is also utilized by all non-United domestic and Canada flights. The facility also includes a British Airways Galleries lounge adjacent to the AeroTrain station, a Lufthansa lounge between gates B49 and B51, and a Turkish Airlines lounge near gate B43. Concourses C and D Concourses C and D are located in the south midfield terminal, and are used for United Airlines flights, including all mainline flights and most United Express regional flights (save for a few that use Concourse A). These concourses were constructed in 1983 and designed by Hellmuth, Obata and Kassabaum. The two concourses have 22 gates each, numbered C1–C28 and D1–D32, with odd-numbered gates on the north side of the building and even numbered gates on the south side. Concourse C composes the eastern half of the terminal and Concourse D composes the western half. The C/D concourses were given a face lift in 2006 which included light fixture upgrades, new paint finishes, new ceiling grids and tiles, heating and air conditioning replacement, and complete restroom renovations. While all gates in Concourses C/D can be utilized for both domestic and international departures, all United international arrivals are conducted at gates C1-C14. These gates