Despite the highly technical name, the Metropolitan Area Outer Underground Discharge Channel is basically a giant hole in the ground. Oh sure, the enormous concrete labyrinth houses the gargantuan machines that keep a vast swath of metropolitan Tokyo from flooding during monsoon season. But still. Giant hole. And seeing it thrilled Christoffer Rudquist to no end.

"It’s pretty exciting to walk around in this big hole and look at it," he says. "Plus, I’m pretty much of a science fiction buff. For me it’s like Blade Runner. It reflected that dystopian future sci-fi in a sense."

That much is true. The elaborate flood control system, nicknamed G-Cans, lies 165 feet below Kasukabe, a city about 28 miles north of Tokyo. Officials claim the network of five silos connected by four miles of tunnels is the largest storm drainage system in the world. Each silo can hold up to 13 million gallons of water, and the entire system can clear up to 7,000 cubic feet of water every second. That's fast enough to drain an olympic swimming pool in 12 seconds.

If that sounds excessive, well, Tokyo sits on the 6,500-square-mile Kanto floodplain, with more than a dozen rivers winding through the countryside. Worse, 30 percent of the population lives below sea level. Early summer monsoons can drop as much as 4 inches of rain in an hour. A particularly catastrophic flood in 1991 inundated 30,000 homes and killed dozens of people. That led to G-Cans. Construction began in 1993, and the $2 billion project took 13 years.

About seven times a year, overflow from rivers throughout the area pours into the silos. From there, it flows through the tunnels into a massive tank with a volume of 248,508 cubic feet. The roof of the tank is supported by nearly 5 dozen 60-foot pillars cast from 500 tons of reinforced concrete. Four turbines, each with 14,000 horsepower, send the water into the Edo River, which flows into Tokyo Bay.

Rudquist loves architecture and industrial machinery, so you can imagine his excitement when Avaunt Magazine sent him to photograph the G-Cans last winter. The government calls it the "Underground Temple," but Rudquist prefers "concrete cathedral." Although a guide accompanied him at first, the fellow eventually let Rudquist explore on his own. Dozens of pillars the size of trees left him feeling like he was caught in an infinity mirror. Sunlight through unseen openings high overhead and the glow of bright bulbs cast an eerie, greenish light on everything. The echoes of a tour group reverberated through the tunnels. “It sounded so surreal,” Rudquist says. “I wish I could have recorded it.”

His epic photos capture the strange, vaguely dystopian vibe of the G-Cans, and make you understand how someone might get so excited about a giant hole in the ground.