Light bridge

Summary
The Forerunners built Halo with many interesting and unknown technologies, one of which is the energy bridge. It is a bridge comprised of "solid" energy, which can support an enormous amount of weight. It is unknown how the energy solidifies enough to support so much weight, though it is possible that the energy particles are simply so dense that objects cannot pass through it.

Images
http://img207.exs.cx/img207/5711/energybridgethumb2xq.jpg