Most buildings and structures are made of brick, cement or other similar material and have a door for entering and exiting the room or area. For than six thousand years, since 4000 BC, ancient civilizations have realized the importance of keeping some areas secure to prevent unauthorized access. These areas are used for storing produce like grains or valuables. Since the doors were used for entering the room, the locking mechanism focused on preventing unauthorized opening of the door. If the unauthorized access to the door were easily detected, it would be a disincentive for the intruder.

In ancient Iran (called Persia) around 4000 BC, a basic system of securing the doors to detect unauthorized access was used. During an excavation of a temple complex at Tall-e-Bakun a number of sealed rooms were found, which were used for storage. The mechanism for closing the door was using a cord that was tied around a peg which was fixed in the door jamb. The cord was then sealed using a lump of cylindrical clay. The seal would have an impression made on it, using a stamp with a particular pattern. The seal would be baked to harden it, so that would not be possible to enter the sealed area without breaking the clay seal.

Though the cord and clay seal would not prevent unauthorized persons from entering the area, the seal condition would provide an accurate indication of whether anyone has entered the sealed area. If the authorized person had entered the area, they would seal the door, after leaving it using the seals provided. If an unauthorized person entered the area, he would break the clay seal and not be able to reseal it. The seals used for the sealed doors were found in a large quantity with specific markings in clusters, indicating a systematic system of using door seals.

It appears that the main principles used for design of locks have not changed significantly since ancient times, thousands of years ago. Though officially the modern lock with a pin tumbler mechanism was invented in the 1840s, it is similar in some ways to the locks which were found in ancient civilizations. In 1925 the Book of Invention for Young Folk was published, with one chapter focusing on the different kinds of locks and keys which were used. The book has details of the various locks which were used in history, using pictures and photos provided by historians researching the various civilizations.

The first diagram in the chapter is that of a lock which was described by Joseph Bonomi in the book “Nineveh and Its Palaces” featuring the palaces in Mesopotamia. The large and heavy wooden lock was discovered in the ancient Mesopotamian palace of Khorsabad. A large wooden key was required to unlock this lock using a mechanism with sliding vertical pins. Similar locks were also depicted in the facade carved in the temples of ancient Egypt. These locks may be made from other material like iron in ancient Egypt. The pin mechanism of these locks is similar to what is found in the locks which most people use for their front door.

There are some websites like Roman Locks which have details of a large number of locks and keys which used in ancient Rome, more than two thousand years ago. It is observed that there are more padlocks designs listed on these roman lock websites compared to door locks. One reason why there are more padlocks could be because the padlocks are more popular because of their versatility and can be used for locking any door whenever required. In contrast there is less flexibility for the door locks. Most experts claim that these roman locks were similar to he locks used at present, though these locks were mostly not having a pin mechanism.

It is observed that some of the padlocks used in ancient Rome were a variation of the warded locks, one of the oldest designs for locks. These warded locks are comparatively simple in design and consist of a number of wards (also called obstructions) which will prevent the lock from opening unless the right key is being used. The key for unlocking has notches of the correct length which will fit in the keyhole of the lock properly. In modern times, the warded locks available are very small locks which are used for locking an inexpensive travel chest, jewelry box , diary or drawers.

Most lock experts do not have much information on lock picking in ancient times, they only have some locks manufactured centuries ago which were found by archaeologists. Using these locks, the locksmith can try to guess the methods which could be used for opening them. Usually skeleton keys are used to open different warded locks, and these keys are specifically made for lock picking. In other cases, these keys can be made by filing an existing key. These skeleton keys cannot be used on modern locks which have a pin mechanism.

Based on the archaeological excavations of Pompeii, in ancient Rome, around two thousands ago, pin tumbler door locks were used for some doors. The Roman engineers modernized the large wooden locks which were used by the Egyptians for more than two thousand years. They replaced the wooden parts with metal parts which were stronger and more durable. Steel was the preferred metal used, and the locks also had steel springs. These locks are considered to be excellent examples of design and precision by locksmiths even today. They open only on one side.

Though the basic locks used today are similar to those used centuries ago, new designs to make the locks burglar-proof have been designed only a few centuries ago. For maximum security steel security doors Echuca are a great modenr option for your Victorian home. Most of the modern locks which cannot be easily tampered with, are fairly sophisticated and a trained locksmith or carpenter will be required to install them. If a property owner is unable to get a suitable carpenter for installing the lock, they usually have to use a padlock, which is easily tampered with in most cases. So there have no major improvements in lock design to keep doors and homes secure in some cases.