No one knew when the tower had been built, or why.� Civilization had risen and fallen so many times over such a span of ages that not even the species of the builder could be guessed.
It couldn't be torn down. � The walls were impregnable.� The only evidence that it could be damaged at all was its jagged top, long ago lost in some unknown disaster.�
And in any case, it would be more trouble on the ground than standing.� On the ground it would be an unbreachable wall several miles long.� Standing, it posed an inconvenience only to birds and aircraft.
In the end, the only thing to be done was to leave it as it was, and add a few warning beacons for passing pilots.
