The changing and developing needs in both offensive and defensive doctrines necessitated the constant study of the art of warfare and fortification, which were essential to the existence and way of life until the modern era. The study of fortifications is an inseparable part of the research of the town planning, the defensive systems and the systems of attack that were available to the city-state and the fortress. The best of the period’s technological developments and tremendous resources were available on the one hand to the developers of the offensive systems and on the other to the designers of fortifications and war machines.

The historical sources aid somewhat in completing the archaeological picture. The preparations for the siege, the moods of the foe and the besieged, a description of the fortifications systems, the various war machines and the turning point in the siege – all these are found in the various descriptions of the siege and we cannot detect them solely with the tools of an archaeologist.

We have at our disposal a significant number of ancient sources which describe with great accuracy the siege preparations and the siege systems themselves. Descriptions of the Greek and Roman authors such as Aineias Tacticus and Philo of Byzantium in their treatises about siege warfare (Poliorketica), or Hero in his essays about the construction of war machines, provide very important information that can be connected to the archaeological evidence.

The development of torsion powered launching devices (projectile and stone catapults) probably in Sicily at the beginning of the fourth century BCE marks a huge change.

The introduction of these machines to the battlefield is a new factor of decisive importance in power equation of the enemy and the besieged which necessitated far-reaching changes in everything concerning the planning and building of the fortification systems in the Greek world. Most of the offensive and defensive effort naturally dealt with the city-states. Both the offensive and defensive systems reached their peak in the second century BCE and have undergone only a few improvements since then. The urban fortification systems of Selinunte and Syracuse in Sicily constitute the height of ingenuity of the Hellenistic-Roman world.

In the absence of excavations at many of the cities of the Hellenistic period, an attempt was made in the past to date and catalogue the urban fortification systems according to building plan and style. This typology has been updated numerous times and the archaeological excavations in the past four decades have contributed greatly to dating and understanding the urban fortification systems.

In contrast with the cities of Asia Minor and Sicily, in the Land of Israel practically no urban fortifications have been excavated that date to the Hellenistic-Early Roman period. The local architects adopted the Hellenistic fortification doctrine as evidenced by the fortifications of Jerusalem, Dor, Akko and Samaria. The fortification in the Herodian period preserved the eastern building traditions while at the same time it adopted the Roman methods of construction. The round tower is perceived as the archetypal symbol of Hellenistic fortification construction since this is the “hot” recommendation of several contemporary authors and because round towers are incorporated in some of the Hellenistic fortification systems. However, the overwhelming majority of the towers of the period are square. It seems that the round tower should be considered, first and foremost, in connection with the building and fortification projects of Herod and his successors. Most of the round towers in the region are built in the period between the middle of the first century BCE and the first century CE.

Despite the influence of the Roman Empire on the region already from the first century BCE, we can discern the new Roman fortification doctrine in the region only at the end of the second century CE and in these instances also this is not manifested in the urban fortifications but in the way the permanent camps for the legions are built.

From the historical evidence we learn that at least some of the cities of the Decapolis were already fortified in the Hellenistic period; however, only recently has the first evidence been exposed of the existence of sections of fortifications of the period. The excavations at Susita have focused in recent years (2006-2007) on uncovering sections of fortifications on the southern and northern sides of the mountain. During these seasons sections of fortifications were located that date to the Hellenistic period and a unique fortification section was exposed from the Roman period (first-second century CE). This evidence constitutes a contribution of sorts in understanding the urban fortification in the Early Roman period in the region of the Decapolis.