25 of Mankind’s Greatest Engineering Achievements(Part 1)

摘要

International Space Station The International Space Station cost$100 billion to build and involved100,000 people in 15 nations.It also ranks as one of the more unusual construction sites,located 354 kilometers(220 miles)above Earth.The hazards faced by those carrying out maintenance go far beyond a falling hammer or nail gun injury——one tiny rip in a protective spacesuit means instant death.Completion date:Ongoing.