The original blanket signals that started the apocalypse went out about two years ago in the game. Some parts of the city are more in tact than others but for the most part, buildings are falling apart and more are getting bombed and destroyed every day. Since it has only been two years, there really hasn't been enough time for the city to have gotten overgrown with plants. Butchers and Dumbshows are pretty much everywhere, while the survivor 'Actuals' are very rarely seen above ground, though they do have to venture out for various reasons

Here are some pictures: 1, 2, 3,