I've always thought that a practical use of mega-structures like Niven's Ringworld (or Halo from the video games), besides colonisation, would be to reach highe

I've always thought that a practical use of mega-structures like Niven's Ringworld (or Halo from the video games), besides colonisation, would be to reach higher energy levels in particle physics, like with the LHC. To reach higher energy levels they need a larger circumference... so if you follow that research to extremes... maybe our descendants in the far future will live on what's essentially a massive science experiment.