Facebook and Apple have transformed Prineville’s visual landscape.

Their data centers overlooking the city have brought hundreds of construction workers to build what officials call the largest projects in Crook County history.

Combined, the tech giants have taken out permits for construction valued at more than $156 million, as of Thursday, according to county building department documents. The value of Apple’s permits totals about $93.2 million, and Facebook’s permits total $63.9 million.

Additionally, Apple late last month applied for a $12 million permit for changes to the first of its two, 338,000-square-foot data centers, which has been under construction since October. The company will get a 15-year break on property taxes, under its agreement with the city and county.

Apple hasn’t said publicly how many full-time employees will work at the data center when it’s done. In a document filed last year, the company indicated it would hire at least 35 people.

The California-based company has kept its data center plans under tight wraps. A wall built around the project obscures much of it from view. Apple officials did not respond to requests for comment this week.

The first of Facebook’s two, 300,000-square-foot data centers has been operational since April 2011. Construction on the second is expected to wrap by the end of the year, said company spokesman Lee Weinstein.

Crook County brings in revenue from fees on a small percentage of the value of each building permit. It’s difficult to put an exact figure on fees collected from the data center projects, county building official Lou Haehnlen said. But they’ve generated enough to let the county bring a part-time building inspector up to full-time.

The data centers are perfect private-sector counterparts to some of the public sector and medical projects on tap for Prineville, Crook County Commissioner Ken Fahlgren said, including a new elementary school and hospital.

“We’ve had tires; we’ve had timber and natural resources. Now we’re adding a tech industry,” Fahlgren said. “It gives not only Prineville and Crook County, but the whole region a chance to see some of the more positive changes we have coming in the future.”

Luring another tech company to build a data center is a possibility, Fahlgren said. The county is working with the state to line up tax breaks on property off of George Millican Road that could entice a large company to build there. Facebook and Apple set up in Prineville after securing similar incentives.