What are the requirements to apply for a Phd. in the US?

Actually, I have completed bachelors in computer science and am currently doing masters in remote-sensing specializing in urban planning. I would like to pursue a Phd. in urban planning domain itself from an esteemed university in the US. Would you like to suggest me any specific requirements and of course, any relevant websites that explain this all.
Any other requirements than TOEFL and GRE?