New York's Empire State Building (ESB) was lit up in green from 12-14 October to mark the Islamic festival of Eid. This Eid (there are two of them in each Islamic calendar year) is called Eid-ul-Fitr and it marks the end of the fasting month of Ramzan (pronounced Ramadan in Arabic). Check out the AFP article about it, the Fox News article about it, and, until the page is updated next, the ESB's tower Lighting Schedule that mentions it as well.
This is only the third religious festival that is honoured by the ESB, the other two being Christmas and Hanukkah. This green lighting (sorry, had to make that pun!) is now going to be an annual event.