Someone wants to build a $700 million data center codenamed Project Mountain in Des Moines, Iowa. It's anyone's guess who's behind it, but Apple and Amazon are the most likely candidates following Facebook and Google into the area. (Update. We now know who it is: Microsoft)

The price tag was found in state documents reported by The Des Moines Register on Thursday. The company behind Project Mountain wants $20 million in tax breaks and plans to create at least 24 jobs.

The Hawkeye State is becoming a hotbed for data centers. Last year a company using the codename Project Catapult bought a chunk of land Altoona, just outside Des Moines, and The Register noted that the city "has fielded interest recently from three or four site selectors looking to locate large data center projects." Facebook confirmed earlier this year that it's the company behind Project Catapult. Meanwhile, Microsoft already has a center in West Des Moines and Google has one in Council Bluffs, about two hours west of Des Moines.

There are but a few companies that could be building a data center of such scale in Iowa. Given that Facebook and Google already are there, that leaves Apple and Amazon as the most likely candidates. Twitter operates at a similar scale but doesn't build its own data centers. Other big tech companies like Yahoo and eBay seem unlikely to expand any time soon.

It isn't unusual to see tech companies follow each other into new areas. When Apple built a data center in Maiden, North Carolina three years ago to support its then-new iCloud service, Facebook followed suit with a center about an hour away in Forest City. At about the same time, Facebook selected Prineville, Oregon for another data center. Now Apple is building a data center across the street.

The House That Jobs Built also is building a data center in Reno, Nevada. It's worth noting, however, that Apple had job postings for the Reno gig posted long before construction began. So far, there's no such listings for jobs in Iowa, which suggests maybe Apple isn't looking to the land of corn and covered bridges.

Amazon has similar taste in real estate. The company opened data centers in Boardman, Oregon in 2011 and most likely is still expanding, though it's expected to build its next data centers outside the U.S.

While Apple and Amazon seem most likely, they're not the only possibilities. For example, Rackspace has been expanding and will soon join Apple, Amazon, Facebook and Google in Oregon. But a spokesperson for Rackspace says the company has no plans to expand into Iowa.

And it's anyone's guess what the NSA is up to, what with that massive data center it's building in Utah and all the data it's siphoning from telecoms and tech companies.

Amazon and Twitter declined to comment for the story. Apple did not respond to our request for comment.