Weyl Invariant Spacetime
  A new class of Weyl invariant backgrounds are presented in terms of the metric $G_{\mu\nu}$ and the anti-symmetric Kalb-Ramond fields $B_{\mu\nu}$. The ten-dimensional spacetime is a product of four-dimensional flat spacetime and curved six-dimensional spacetime having nonvanishing Ricci tensors. The non-vanishing Kalb-Ramond field strengths cannot be written globally as $H=dB$, being of the monopole type. Nevertheless they define homogeneous spacetime with no singularity. 
Yutaka Hosotani