The distinctive, red-and-white-striped steam stacks of the Scattergood Generating Station in Playa del Rey, visible from miles away, have been a landmark for decades. They also point to one of L.A.'s less lovely but critical pieces of infrastructure, the Hyperion Treatment Plant. There are free walking/tram tours of the facility; visitors are warned in advance that the smell may be overpowering for some. So how bad could a sewer serving 3.3 million people really smell? In the 90-minute tour, visitors encounter stench levels from mild to truly appalling. It's an interesting experience. Everyone puts on hard hats and follows a nice lady, who explains everything that happens in the plant, and who probably gets tired of people making bathroom jokes and retching sounds. You see and learn more than you ever imagined about what happens after you flush — especially at the “headworks,” where you get right up close to the dripping Jaws of Sludge as they lift and separate all manner of unidentifiable objects from the gray, gooey fluid. Don't bring a date to this one. 12000 Vista del Mar, Playa del Rey. (310) 648-5363, lasewers.org/treatment_plants/hyperion.