Then turned attention to other things. Simply hoped that F.N. would never bomb warrens. Some warrens, L-City in particular, were so deep down that they could probably stand direct hits. One cubic, lowest level of Complex where central part of Mike lived, had been designed to withstand bombing. On other hand Tycho Under was a big natural bubble cave like Old Dome and roof was only meters thick; sealer on under side is kept warm with hot water pipes to make sure new cracks sealed—would not take much of a bomb to crack Tycho Under.