It’s no secret that technology and the people who build it have made some pretty impressive advances over the years, but while there are plenty of smaller, incremental advances that change our lives in some minor way, there are a handful of giant mega projects which have helped transform the world around us.

Whether it’s rocketing us into space, bringing us all together, building astounding edifices, or answering fundamental questions about who we are and where we come from, here are our picks for nine of the most ambitious tech projects in history.