A building which cost $1.5 billion and was 20 years in the making was moved into position over the highly radioactive remains of the main reactor at Chernobyl this week. The time lapse video above shows how the building was inched into place.

The new structure, which is about 500 feet long, has a span of 800 feet and is 350 feet high, is designed to last at least a century and is intended to prevent any additional spewing of toxic material from the stricken reactor.

Even with the building in place, the surrounding zone of roughly 1000 square miles will remain uninhabitable.