Yes, this isn't a massive underground temple, but rather a futuristic sewer system in Japan, the Metropolitan Area Outer Underground Discharge Channel to be exact. It consists of massive 65m x 32m concrete silos connected by 6.4km of underground tunnels 50m below the surface. Continue reading for a video, more pictures, and additional information.
Work on the project started in 1992 and was completed by early 2009. It consists of five concrete containment silos with heights of 65 m (213 ft) and diameters of 32 m (104 ft). It is connected by 6.4 km (4 miles) of tunnels, 50 m (164 ft) beneath the surface. There is also a large water tank (shown above) with a height of 25.4 m (83 ft), a length of 177 m (581 ft), and a width of 78 m (256 ft). There are 59 massive pillars connected to a number of 10 MW pumps that can pump up to 200 tons of water into the Edogawa River per second.
[Sources 1 | 2]