Everyone thought it was pretty hilarious in 2006 when Ted Stevens described the internet as a "series of tubes." Turns out that's pretty much what it is, though, as Andrew Blum illustrates in his new book about the physical infrastructure of the internet. It's not all tubes—there are also big machines that look like fancy filing cabinets, and lots of black boxes with flashing lights on them—but the point remains: The internet has a physical infrastructure designed to move bits of information from one point to another. It's just stuff plugged into other stuff, all over the world.

In the introduction to Tubes, Andrew Blum cites a "folk cartography" project that asked people to draw a picture of the internet as they conceive it. The results varied wildly: Some people drew the internet as a mesh, some drew rings, some drew "a cloud or radial like the sun." No one, Blum points out, drew the actual machines, cables, and—yes—tubes, that actually comprise the internet.

Blum, who has written about architecture for the New Yorker and the New York Times, sets out to create his own map of the internet, to "stitch together two halves of a broken world—to put the physical and the virtual back in the same place." His exploration of the physical internet takes him to Virginia, where a crucial hub called MAE-East allows different networks to connect with one another; to Manhattan, where he considers the underground hive of telecommunications cables; and to Portugal, where he observes the installation of an undersea cable connecting Lisbon to the coast of Africa. Then it's on to Oregon, where he finds at the Dalles "one of the internet's most important repositories of data"—the city houses giant data centers, thanks in part to a cool climate that helps offset the heat generated by all those hard drives. These data centers store our emails, online backups, Facebook accounts—everything we think of as belonging to the "cloud." But "there's nothing cloudlike about it," Blum points out. There are, instead, facilities like Google's secretive campus, where a tight-lipped "tour guide" declines to share any actual information about the facility. (Data centers, Blum says, are notoriously secretive, as technology companies try to keep competitors from realizing how big they are, how much power they use, and exactly what kind of information they store. His experience at a nearby Facebook data center, in Prineville, is far more positive.) It's observations like these—that "the cloud" is actually a place, in the Dalles—that have the strongest potential for changing the way readers think about the internet.

Tubes' biggest problem comes from the sheer size of Blum's undertaking. He throws around a lot of names and a lot of terminology, overexplaining some things while underexplaining others; Blum is an excellent pop-science writer but tends to lose focus when it comes to the harder stuff. The book would also benefit tremendously from a photo or two—even if the internet does, as Blum says, generally resemble a self-storage warehouse.

But while Blum occasionally gets bogged down in names and technicalities, he regularly tempers the tech-talk with descriptions of the cities he's visiting—Amsterdam, he tells us, isn't all "whores and hash"—and the people he's met, the personalities who have driven the internet's development. (Another key insight is how much the development of the internet has been based on networking between people, not just machines.) And it's ultimately successful in its basic endeavor: to convince the reader to think about what happens when they type a query into a search bar, to think about where that query goes, who responds, and from what point on the map.