If you look closely enough on Google or Bing Maps, some places are blanked out, hidden from public view. Many of those places disguise secret or sensitive American military facilities.

The United States military has a foothold in every corner of the world, with military bases on every continent. It's not even clear how many there are out there. The Pentagon says there are around 5,000 in total, and 598 in foreign countries, but those numbers are disputed by the media.

But how do these facilities look from above? To answer that question, you first need to locate the bases. Which, as it turns out, is relatively easy.

That's what Josh Begley, a data artist, found out when he embarked on a project to map all known U.S. military bases around the world, collect satellite pictures of them using Google Maps and Bing Maps, and display them all online.

The project, which he warns is ongoing, was inspired by Trevor Paglen's book "Blank Spots on the Map" which goes inside the world of secret military bases that are sometimes censored on maps.

"I wanted to apply this to a digital landscape," Begley told Mashable. "What are the actual blind spots of Google Maps or Bing Maps? Which installations are secret and which can be viewed on the open Internet?"

Begley has found the coordinates for 650 bases, and published pictures for 644 of them — although a few are blacked out, not displayed, or blurred.

He started working on the project at the beginning of November, simply armed with the Department of Defense 2013 Base Structure Report, an inventory of all the real estate owned by the Pentagon around the world, a few media reports that uncovered secret bases, and a computer script he had used last year to make another mapping project that displayed aerial pictures of U.S. prisons.

He modified that script, which he made along with his friend and fellow digital artist Jer Thorp, to grab a series of coordinates from a database file, query the Google and Bing maps' APIs, and automatically capture a satellite picture of that spot. Sounds easy enough, but some publicly available coordinates aren't particularly precise, so Begley had to manually take screenshots for those (and he still has to finish correcting some mistakes).

This manual work was also necessary in cases where the bases are secret, or at least not officially acknowledged by the U.S. government. The CIA site that independent journalist Jeremy Scahill uncovered in Mogadishu, Somalia, or the secret drone base unearthed by Wired's Noah Shachtman earlier this year are examples.

Begley had already included a picture of a highly classified facility in Qatar before U.S. Defense Secretary Chuck Hagel officially revealed its location on Tuesday — even though it had been something of an open secret.

Which leads us to the question: Is any of this actually a good idea?

Google Earth satellite pictures were reportedly used to pinpoint a target by terrorists who killed 164 people in a tragic attack in Mumbai, India, which prompted some to call for a ban on publishing these types of pictures.

"Google and Microsoft and every other commercial provider should be barred from photographing and displaying military bases," Computerworld's Patrick Thibodeau wrote at the time. "We are building intelligence capability for our enemies."

But experts disagree, and don't see Begley's site as something to worry about.

"The capability to acquire and publish such imagery is simply a fact of life that military forces and others have to adapt to," said Steven Aftergood, an expert in secrecy and researcher for the Federation of American Scientists.

This capability can theoretically be used to plot terror attacks, he explained, but it can also provide great geographical insight.

"In an open society, we take the good with the bad," he told Mashable.

"I’m sure it’s not welcomed by the DoD," said Joe Francica, the editor in chief and vice publisher of Directions Media, a publication that covers geospatial technology. "But if you are in intelligence at Al-Qaeda, somebody probably has done this already."

A Department of Defense spokesperson didn't respond to Mashable's requests for comment.

Begley, on his part, said he would understand if someone criticized the project, but he doesn't see anything wrong with it.

"I'm mostly just posing the question," he said. "[The website] really is just a highlight of things that are already available on the Internet."

Moreover, it's not unprecedented. In 2000, pictures of the once secret Area 51, taken by a Russian satellite, were leaked on the Internet.

Nobody owns the skies above secret bases, so there's no law that prevents privately-owned or public satellites from snapping pictures from space. But when it comes to publishing them, secrecy can still prevail.

Google Maps, for example, doesn't show an image for the secret drone base exposed by Wired. But Bing does.

And in other cases the censorship — for lack of a better word — can be even more imaginative, as it is with images of the Volkel Air Base, a military base in the Netherlands.

These are cases in which Google and Microsoft were asked not to publish a clear image of the sites. The two companies declined to answer specific questions about the sites, and about Begley's project. But they explained that sometimes, it's not up to them to make these kind of calls.

"Google Earth is built from a broad range of imagery providers, including public, government, commercial and private sector sources — some of which may blur images before they supply it to us," said a Google spokesperson.

Microsoft, on its part, explained that sometimes it is required to delete or blur images. "We work with our imagery collection vendors to ensure that they comply with applicable laws," a company spokesperson said.

Take a look at the most interesting aerial views, as chosen by Begley himself, in the gallery below.

U.S. Military Bases From Above

Image: Google Maps