It is a mistake to assume that security levels could be increased just by improving the equipment of security, military and police forces.
Eavesdropping and security have been important activities for the security of all sorts of installations for many centuries as well as for the survival of military forces: after the first religious temples appeared during the last stages human prehistory (approximately at 4.500 B.C.), the first defence forces made an appearance too in the incipient but prosperous little towns that were growing in places like Sumeria; this constitutes one of the better studied cases in this regard.
For the Sumerians, security comprised many different levels of vigilance: of course, they had soldiers and warriors ready to protect the kingdom's assets, but they had other means, which they considered very important as well, including spells, fetishes and other items designed or devised to protect them against bad omens, spirits and so on.
It is wrong to assume that equipment will determine the odds of survival; it is also incorrect to think that training or physical abilities will make any decisive difference. Indeed, all these factors may contribute to make things easier or not, but the most fundamental thing is motivation; beliefs have more strength than empires. All along history it has been demonstrated several times that the best way to protect something is by believing in it and so Macchiavelli once wrote that the greatest men are those that create religions, followed by the builders of nations and businesses.
Of course, modern security systems may protect somewhat any sort of installation; however, they will never be enough to supplant altogether the beliefs of the guardians. Thus, planning in terms of security means the creation of adequate motivation and troop morale mechanisms. The preservation of almost any sorto of heritage depends on the culture of the inhabitants or the people surrounding it.
A statue representing the Sumerian king Gudea - made around the year 2.100 B.C. - portrays some well-preserved cuneiform inscriptions that describe the reconstruction of a temple, placing also a haunting against all sorts of evil-doers such as vandals and robbers. It seems that somehow it worked just on pure belief, for the statue reached our days in a fairly good state of preservation.
Now... What kind of security technology could preserve anything like that for more than forty centuries?