The present day

The small girl sat bruised, bleeding and crying in the gutter. Her grandfather looked up, forlornly, at the great empty stone building towering above them.

It had emerged undamaged from all that this once great city had endured, as if nuclear war and alien attacks had been nothing more than mild summer rain. Now it was the only building still standing in this part of the City.

The great stone edifice was just exactly as her grandfather remembered it, when it first arrived.

The old mans thoughts turned to the past.

Quite some years earlier

They came unheralded.

One second there was vacant land, in decaying urban areas, and the next, impressive stone edifices sat squarely upon the land. Teleported in place from lord knows where. One such edifice was transported for each of the truly major cities of the Earth.

It was thought that someone or something must have come earlier to survey likely locations for the buildings, unless of course those who arranged for their transportation were both omnipotent and omniscient. Which may well have been the case.

All the buildings arrived at exactly the same moment, give or take a milli-second.

They opened for business on the next calendar day after their arrival in strict alignment with normal business hours and conscious of the Earth time zones they had been located in.

Not that the buildings were ever truly welcome, but a few individuals overcame their fears and availed themselves of the services offered within. Nobody that did so ever complained. However Governments, almost universally, discouraged their citizens from using the buildings.

The great edifices did not interface with the cities they occupied. They were not connected to city power sources or water supplies, or sewage, or stormwater systems. No goods or equipment of any kind ever entered them, only the people who sought out their services.

Other than imposing a news blackout and establishing "no go" areas around the buildings, Governments had been powerless to do anything about them or those who occupied them. For the most part authorities chose to ignore the buildings. Also most people were mistrustful of the buildings and the vast bulk of humanity never went inside those doors.

Just a few Governments authorised military attacks against the buildings in their cities. Though there had never been any evidence of force shield protection the edifices proved indestructible. Not so much as a single one of the large stones used in their construction was even chipped. This was clearly no stone of Earth and theories abounded as to their nature. Even suggestions that they represented a fourth or fifth state of matter.

Other Governments, while avoiding crude and useless direct assaults, had made subtle and not so subtle attempts to obtain chips or flakes of the stone material. Or any other material that they could take away to analyse. Frustratingly their efforts bore no fruit and, sooner rather than later, they gave it away.

The buildings seemed to be fully self sustaining for whatever occupants they housed. None of those who presumably worked and lived within were ever seen outside the premises. Possibly the occupants had extra-dimensional access to additional facilities but this was never more than speculation. Even those who entered the edifices learned nothing of significance.

There had been no way of knowing how many of the advanced entities had occupied each building. Eventually the view prevailed that the buildings had been sent for a greater purpose. A purpose that never eventuated. It was generally thought that individual entities teleported into and out of the buildings with comparative ease, so that at any one moment one or even all of the buildings on Earth could have been unoccupied. In truth, no one knew.

Then years later still, and just as suddenly as they had come, all but one of the buildings disappeared. The one remaining edifice being located in New York City.

At some point after this, the occupants of this last building stopped providing services and gave no external evidence of habitation. It was generally presumed that they had gone.

The Present Day Again

"They are coming" said the small girl "the noise is getting louder all the time."

"I know" said her grand popthinking to himself there is nothing we can do and we have nowhere we can go.

The man looked wistfully at the magnificent building. If only he and his daughter could get inside its protective embrace, even for a few days.

He briefly recalled a time when, faced with an earlier alien scavenger invasion, the authorities made their last and best and most determined efforts, which included high powered tight beam laser drills, to enter the empty building standing before him. Not for its secrets, but just to provide a haven for the flood of refugees.

Now, high above them, one of the current alien scavenger invaders star ships came slowly into view. The man was unable to judge its size and altitude but knew instinctively it had to be massive. He and his granddaughter moved to the opposite side of the huge building and hunkered down very close against its walls.

At just that moment energies, unknown and possibly unknowable to men, lanced from the star ship to the huge building. They had no more effect on the structure than had mans even punier efforts of years ago. There was no collateral damage; no reflection of energies, rather the edifice efficiently and totally absorbed every single erg of energy sent its way.

The star ship was persistent, but that persistence was not rewarded. Where the energies had hit and been absorbed by the building there was not the slightest evidence of burning or scorching or damage of any kind. Had anyone been there to touch the stone immediately after the attack it would not even have felt warm.

As the star ship ceased its energy discharge, so the first of the alien scavenger ground troops came into view. Since there was nothing much else hereabouts the grandfather assumed that the stone edifice must be their prime target.

Just then the small girl tugged insistently at her grandfather's elbow. Distracted by the advancing ground troops he seemed not to notice. She persisted.

"Someone has turned on a light in the building" she yelled trying to get his attention. He turned and through one of the dense but semi-transparent apertures that men had assumed were windows, a dull light could be seen where there was none before. It could be automatic thought the man, not wanting to get his or his grand daughters hopes up. Or perhaps someone had teleported back in he thought a caretaker or security guard or some such, just checking on things

The old mans heart began to beat heavily with excitement, increasing to dangerous levels as one of the large, ground level, door like, apertures began opening slowly. It was through these apertures that some humans had once entered seeking the services dispensed within.

The scavenger alien ground troops had paid no heed to the light within the edifice but slowed visibly as the door aperture began to open.

Then much to the disappointment of man and child the door closed again and before they could even draw another breath the mighty stone building was gone.

Long ago the occupiers of the stone edifices had recognised the failure of their grand design for Earth. It had been based on the unrealistic assumption of a high level of human cooperation. Quite the contrary obtained and the advanced entities were slow to recognise this and not prepared to force matters.

Still, as long as the single stone edifice remained, even unoccupied, the link, however tenuous, between man and the highly advanced creators and transporters of the edifices had remained. Now, as a result of a reluctant decision made at an inconceivable distance from our world, one of their number had returned to finally severe, for all times that last tenuous link. The entities had washed their hands of us.

Having forgotten about the current scavenger alien invaders for the barest moment, grandfather and granddaughter, hands held, turned to face certain death, only to find that these lesser aliens and their star ship above were also gone.

In that final act of severance the near omnipotent edifice creators/transporters bestowed one last gift on man. The complete removal of his immediate enemy.

From now on though, we were unquestionably on our own.