Workers walk by a shelter and containment area built over the destroyed 4th block of Chernobyl's old nuclear power plant on Aug. 25, 2013
The concrete sarcophagus encasing Chernobyl was built in only 200 days, under extremely radioactive conditions, and never meant as a permanent solution to the fallout. Currently, rainwater seeps in through the crumbling structure, weakening it and threatening to set off another explosion inside the reactor. Work on a new shield has been delayed time and again, but in November 2012, the first sections of the so-called New Safe Confinement were finally raised. When completed, the 360 x 820 x 490 feet steel hanger will be slid into place over the existing sarcophagus, making it the largest moving structure on earth. Built to last a hundred years, the behemoth is meant to give workers time to deconstruct the reactors, which will then be moved to a permanent burial location.