Located 26 miles west of DC, in Virginia. It's DC's larger airport, and handles most international flights. The Metro does not go to Dulles (though it will by 2020), so Metrobus 5A and the Washington Flyer Silver Line Express Bus (combined with a Metro ride) get you to downtown DC. Both take around 60 minutes and cost $7.50 to $11. Taxis cost around $67.
Dulles has free wi-fi, several currency exchanges and restaurants throughout the terminals. Famed architect Eero Saarinen designed the swooping main building.