When the great pharaoh, Khufu, died the priests sealed his mummified body and a rich collection of his most valued possessions inside the Great Pyramid at Giza. As they sealed it shut, the priests must have thought that such a fortress of limestone and granite would keep the grave robbers at bay for all eternity. They could never have imagined that thieves could ever ransack the world's strongest tomb. They could never have imagined losing the great Pharaoh's treasure forever, or that his body would find its resting place in an apothecary's shop, ground up for use as a medicine.

The priest's failure to keep Khufu's tomb secure shows that if the potential rewards are great enough, no building can hope to keep the criminal at bay. An ingenious criminal will always find a way in to a building, however secure it may seem. Yet Khufu and his treasures might have remained intact if as the priests had put as much thought into keeping the thieves in as they had to keep out.

If the rewards justify the effort involved, today's burglar, like his ancient Egyptian counterpart, first identifies the quickest, easiest and safest route into a building. In a third of burglaries he will get in through a rear window.

Windows are often the weakest point in the house, and the back of the house offers the best protection from prying eyes.

His biggest fear is of getting caught. Every second that he is in the house he is running the risk of discovery. His escape route is his lifeline. If he can get his head through an open window, a burglar can easily worm his way into the house. Getting back out with an angry householder snapping at his heels is more difficult. These rats need bigger holes to scurry out of and holes in houses do not come bigger than the doors.

With most householders now security conscious securing an escape route should be the burglar's greatest challenge. Millions of pounds of government money goes into making the public aware of the benefits of good quality locks on doors and windows. Most security professionals recommend five-lever mortice deadlocks on both front and back doors, with strong, bolts top and bottom. For front doors most also recommend automatic deadlocks that you can lock from the outside. As well as locks, they also recommend fitting laminated glass to windows and doors, and key-operated window locks.

The advice is sound. A burglar is unlikely to risk attracting attention by smashing a large pane of glass. He will, however, smash a smaller pane of glass in a window to reach through and slip the latch. Window locks provide the window with multiple locking points that prevent the burglar prising open the window or opening it from the inside. Mortice locks and deadlocks make formidable obstacles for those without the keys.

A determined burglar may well manage to get inside a house, even when the owner has followed such crime-prevention advice. Once inside, however, he will face the difficult problem of getting back out with anything larger than an ornament or two. He might have free run of the house while his courage holds. He might rifle through all the cupboards, cabinets and drawers for items of value. But if the owner has taken sensible precautions, they will have hidden all small valuables in a floor safe or other secure place. Larger valuables such as electrical items and furnishings are less conveniently hidden away.

However big-headed the burglar may be, he will never persuade a grandfather clock or LCD television to squeeze through a small kitchen window.

Fortunately for the burglar the bolts inside a door are useless if he can touch them. And the most secure lock is worthless if all he has to do is to turn a key to open it. As he climbs out of the French windows with your computer he no doubt gives thanks to St Gates, the patron saint of windows, that an unlocked window-lock offers similar security to a cardboard safe.

Despite government advice, in two out of ten burglaries an unlocked door or window means the burglar does not even have to use force to get in. More alarming is that once inside the burglar often has no trouble at all in getting back out by a door or a larger window.

All too often the police attend the scene of a burglary to find the burglar who has struggled to squeeze through a small window has simply walked out through a door. The door will often have a key in the lock, "in case there's a fire", or a simple latch lock the busy householder lazily pulled to on the way out. Occasionally the unwitting occupier will have even provided the burglar with a getaway car in the drive and the keys on the kitchen table.

None of us can build ourselves a pyramid. None of us would want to live in the dark, suffocating confines of windless fortress. However, all of us can make sure the burglar leaves with no more than a sense of frustration simply by making it as difficult to get out of the house as it was to get inside.

Keys nesting in a basket in the kitchen attract a burglar like baby birds in a nest attract a cat. Keys impaled on hooks behind the door soon prove efficient traitors. Sheathe keys in their locks and you stab at the heart of your home security. Deposit your spare keys with family or good neighbours, or hide them away in a strongbox with any other small potential pickings.

The Great Pyramid's six million tons of stone make it the most massive building ever built. Its purpose was to protect Khufu and his possessions into the afterlife, and it failed. Yet our modest homes, frail in comparison, can far more successfully guard our assets if we take the right precautions. Allow a burglar access to your house keys and your household security becomes as effective as the medicine made from Khufu's stolen mummy.