City 17

City 17 is a grand city in Eastern Europe (probably located in former Sofia, Bulgaria) that has existed since before the Seven Hour War. Later taken over by the Combine, it became their main headquarters on Earth.Dominated by the imposing Citadel and surrounded by the desolate Wasteland, it is the only location in Half-Life 2: Episode One, and one of two major locations in Half-Life 2. It also made an appearance in Half-Life: Alyx.