This one is supposed to be bigger still (4b lightyears):
Biggest Thing in the Universe - Sixty Symbols
... but I don't know if it's been confirmed or refuted since it was announced (3 years ago).
But one thing is for sure: the assumption of homogeneity on large scales is flawed. Perhaps not so for the very early universe but cosmological evolution from small fluctuations promotes a fractal geometry, where there is structure on all scales. Of course the subtle fractal structure was there in the first place in the fluctuations about the near-homogeneous mean. The CMB confirms this.