Is this Apple's Bloom Energy fuel cell plant? These new foundations could hold racks of 200-megawatt fuel cells, according to Gary Cook, an IT analyst with Greenpeace who has been following Maiden closely. Apple had said that the fuel cells could start coming online as soon as June, but clearly that has not yet happened. Here is Apple's new tactical data center. This 11-room facility seems to have a few extra security measures. It includes "man traps," meaning that visitors will have to walk through two sets of security doors to get inside, and it's bordered by its own 8-foot chain-link fence. Those five long white units at the bottom of the photo are diesel backup generators. Another look at the tactical data center. New solar panels going in across the road. Another look at Apple's 100-acre solar farm. Apple seems to be using dirt from this mound to build an earthen levee around the new structure.

Apple is building something new at its Maiden, North Carolina data center, and thanks to our 1949 Piper PA-11 (Cub Special) iSpy Plane, we can give you an exclusive first look.

In our photos, taken Monday, you can see construction crews laying the foundations for a new approximately 20,000-square-foot structure in a wooded area just northwest of the main data center. Apple appears to be finally building its 4.8-megawatt array of Bloom Energy fuel cells, which convert biogas into electricity.

Apple is one of many web giants that are now building their computing facilities in an effort to save both money and power, including Google, Amazon, Facebook, and Microsoft. In many ways, Maiden is the model of the modern data center. It's home to a mammoth 500,000-square-foot building that houses rack after rack of Apple servers used to power the iCloud, but Apple is also tacking on a few extras that you won't find in most data centers: a 100-acre solar farm, and an array of Bloom Energy fuel cells.

But while Apple promotes the data center as the very model of energy self-sufficiency, it has come under fire from Greenpeace for situating the data center on Duke Energy's power grid, which provides cheap energy that is largely generated by coal and nuclear generators.

Of course, the notoriously secretive Apple doesn't like to answer questions about its data centers, so we've had to take to the skies to figure out what's going on. On our first flyby back in May, we could see that something was being built right next to the main data center. Back then, we guessed it was the site of the fuel-cell farm, but regulatory filings proved us wrong.

It turns out that this 20,000-square-foot building, located just south of the main building, is what Apple calls a "tactical data center."

Nobody knows exactly what an Apple tactical data center is supposed to be, but according to Rackspace Chief Technology Officer John Engates, who has spent his fair share of time in windowless buildings racked with servers, it may be a neutral spot where Apple partners can come and plug their gear into Apple's grid without getting any exposure to the fantastic secrets housed in the larger 500,000-square-foot facility.

Our flyover captured some pretty clear images of the tactical data center, the massive solar array, and, of course, this new mystery building (see photos above).

Photos: Garrett Fisher/Wired