Data centers are the backbone of the digital economy, which is experiencing astronomical growth. (The total number of websites alone is expected to exceed 1 billion this year). At 3 million data centers in the country (and counting), fewer than 10 facilities will account for 72% of all data center construction in the world. Here are the top six.

Facebook Prineville

Owner: Facebook

Location: Prineville, OR

Size: 1.1M SF

Facebook invested a whopping $780M in buildings and computers for its first data center in Prineville, which opened in 2011. Since then, Facebook has opened new data centers in Forest City, NC; Lulea, Sweden; Altoona, IA; and Forth Worth, TX. The company's massive data center network stores all the information for its 1 billion daily active users.

Bumblehive

Owner: NSA

Location: Bluffdale, UT

Size: 1.1M SF

Sandwiched between Utah's Wasatch Range and the Oquirrh Mountains, this $1.5B facility has been called the world's "largest spy center." Opened in 2013, the NSA data center intercepts, analyzes and stores all forms of communication—think private emails, cellphone calls and Google searches—in order to prevent cyberattacks and other threats to national security.

The Lakeside Technology Center

Owner: Digital Realty Trust

Location: Chicago, IL

Size: 1.1M SF

The Lakeside Technology Center is the nerve center for Chicago’s commodity markets; its tenants include Chicago Mercantile Exchange and Equinix, as well as other financial institutions. The building was originally built to house printing presses for the Yellow Book and Sears Catalog before being converted to telecom use in 1999.

Digital Realty Ashburn Campus

Owner: Digital Realty Trust

Location: Aushburn, VA

Size: 1.5M SF

In 2007, Digital Realty broke ground on its first building in Aushburn. Fast forward to today, the Aushburn Campus consists of seven state-of-the-art buildings, with one more under construction and room for two more—a project that cost Digital Realty a total of $9.5M over the years. The company supports the data center strategies of major financial institutions, technology companies and cloud providers.

Ashburn Corporate Center (ACC)

Owner: DuPont Fabros

Location: Ashburn, VA

Size: 1.6M SF

The Ashburn Corporate Center campus consists of six buildings in the heart of Northern Virginia's Data Center Alley. Over the years, DuPont has invested about $1.2B to expand the campus. The latest facility, ACC7, was opened in 2014: it boasts 446k SF and can provide as much as 41.6 megawatts of power.

Las Vegas Supernap Digital Exchange Campus

Owner: Switch

Location: Las Vegas, NV

Size: 2.4M SF

Switch's Supernap campus in Las Vegas is the largest technological campus in the nation. The Digital Exchange Campus comprises nine buildings—with three more on the way—producing as much as 310 MVA of power. In addition, Switch is building an additional 6.5M SF of data center space in Reno, about 450 miles from the current campus, which will become the largest data center facility in the world.