It depends on what you mean by big the only city in Armenia that is a city by American standards is the capital city, Yerevan (Երեվան). After that, by size, the next biggest cities are Gyumri (Գյումրի) Vanadzor (Վանաձոր) and Hrazdan (Հրազդան). I hear Kapan in the south west is also very large, but Ive never been there, and it isnt really considered part of Armenia anymore.