What is the nature of work at area 51?

Doing a college research paper, my choice of topic, and I chose government cover-ups/myths. The last subject is going to be Area 51/Groom Lake as I've been told its now called to fend off any would be conspiracy theorists today. Just wondering if there's any declified intel that I could put into the paper? Nature of the work, ets inside 50 years ago?? any info would be much obliged!!!