CityVille is officially the most popular Facebook game of all time. The Zynga title has over 100 million active users, putting it ahead of FarmVille and its 57 million monthly users.

CityVille launched on December 2, 2010 and gained 26 million users in two weeks. While the game is driven by in-game purchases, it seems likely to become a target of promotional collaborations, just like FarmVille and Mafia Wars.

Source: Casualgaming.biz