Get it into orbit and use it to tether (and as material for) a space elevator.
Now, space elevators are another topic. We don't have the materials right now but fun stuff like if one collapsed, it would wrap around the world a couple of times (IIRC).
This is stuff we're working on...it was the whole point of our seastead in Thailand.
https://en.wikipedia.org/wiki/Launch_loop
It would need to be done in the ocean.
Strangely enough, about a week before the Thai navy came after us a friend of mine told me that he has had friends killed who were trying to create technology to go into space.